Strange Issues After Changing Head Gasket

After getting symptoms of a blown head gasket a few weeks ago, left the engine in the car and replaced the head gasket, water pump, PCV valve, cleaned out the EGR system (cooler, pipe, valve, air intake passages). I got it all back together and it seemed like it was running great as I ran it as I put coolant in it and bled the system. After the coolant and oil were topped off and everything looked good, I drove it around the block and everything looked good.

So I thought everything was set and done. Later that night I decided I was going to test it out on the freeway before I went to bed so with it still warmed up I started it up and drove it to the freeway, and when I got it on the on ramp, I accelerated up and when I got up to about 60 mph I felt a shake in the engine compartment, the check engine light was blinking and I got a Check Hybrid System alert. I didn't have my ODB2 connector with me to read codes, so I slowed down and took the next exit, I was only on the freeway for a 1/2 mile. After I got off and stopped, I took a right and the car died. I started it and stopped it three times and it cleared the hybrid error and it sounded and acted just like normal, and I drove back home in the country roads going 40 mph with no issues and parked it.

I put a code reader on it and these were the codes I saw:

• P0351 - Powertrain - Ignition Coil "A" Primary/Secondary Circuit
• P0352 - Powertrain - Ignition Coil "B" Primary/Secondary Circuit
• P0353 - Powertrain - Ignition Coil "C" Primary/Secondary Circuit
• P0354 - Powertrain - Ignition Coil "D" Primary/Secondary Circuit
• P3190 - Powertrain
• P0032 - Powertrain - H02S Heater Control Circuit High - Bank 1 Sensor 1
• P0038 - Powertrain - H02S Heater Control Circuit High - Bank 1 Sensor 2
• P0300 - Powertrain - Random/Multiple Cylinder Misfire Detected
• P0301 - Powertrain - Cylinder 1 Misfire Detected
• P0302 - Powertrain - Cylinder 2 Misfire Detected
• P0303 - Powertrain - Cylinder 3 Misfire Detected
• P0304 - Powertrain - Cylinder 4 Misfire Detected
• P0121 - Powertrain - Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem

That was a lot of codes, and they didn't appear after I cleared them and drove it around again so I was confused on what was my problem. I checked all my plugs to make sure I didn't have a sensor unplugged. I checked all the coils and the throttle body and mass air flow sensor, and everything was tight. So I just left the car for a week or so to give me a little rest, I was a bit beat up after the over haul and then being hit was this, not fun.

After getting some more free time to do more troubleshooting I got Techstream loaded up on the laptop and did some tests, and this is what I found.

Idling
Sometimes when it is cold the engine will start right up and run for up to 20-30 minutes (in maintenance mode non stop, or shutting on and off in normal mode) without any issues. Other times whether it is cold (20-30 degrees) or recently started it will run for 10-30 seconds or 1-5 minutes and then start misfiring and then stop the engine.

Driving
Same as idling, it will drive 5-6 miles sometimes without any misfires or very few, maybe 2-10 in a 10 minute drive with only one or two happening very distant away from another. Other times it will drive 10 feet and then start shake and misfire and it seems like the car shuts the engine off and throws the Hybrid System error every time it misfires like that, all four cylinders. It can do it while driving at a steady speed, accelerating, idling at a stoplight, or stop sign. After it happens if I can pull over and do a stop restart three times to clear the Hybrid system error message it will usually run fine for a bit. Sometimes it won't misfire for a few miles, sometimes it will after just a 1/2 miles, so it is a bit random.

At first I was cautious as accelerating since that is when I had issues the first time, but I have successfully floored the accelerator pedal and the engine will accelerate very quickly just fine and I have gotten the car up to 60-70 mph without issues, so it does appear to just be random times when it will just start to misfire and have coil pack issues.

The things I am seeing in Techstream over and over is the four coil pack errors, misfires in different cylinders and the Throttle/Pedal Position Sensor/Switch. No real Hybrid errors in the Hybrid system section, other than P0A0F - Engine Failed to Start.

• P0351 - Powertrain - Ignition Coil "A" Primary/Secondary Circuit
• P0352 - Powertrain - Ignition Coil "B" Primary/Secondary Circuit
• P0353 - Powertrain - Ignition Coil "C" Primary/Secondary Circuit
• P0354 - Powertrain - Ignition Coil "D" Primary/Secondary Circuit
• P0301 - Powertrain - Cylinder 1 Misfire Detected
• P0302 - Powertrain - Cylinder 2 Misfire Detected
• P0303 - Powertrain - Cylinder 3 Misfire Detected
• P0304 - Powertrain - Cylinder 4 Misfire Detected
• P0121 - Powertrain - Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem

Here is what the engine sounds like without any misfires
https://1drv.ms/u/s!Aoge5dkm9gDIitkyJ9vSjMS7ToCFpA?e=yF1GP3

Details on Coils
Not all the cylinders will sense a misfire everytime, but all coils will throw an error and so will P0121. When I was taking the spark plugs out, the bottom boot of the coils got stuck on the spark plugs and they got mangled up so, I instead of getting new boots for my existing coils, my brother just got new coils for his Gen 3 Prius, but it had head gasket issues and he ended up selling it and keeping the coils, so I got those from him, since they were almost brand new and put those in when I replaced the head gasket. I am thinking maybe the coils I got from him had some issues, and I am wanting to put the original coils back in as a test to see if that changes anything.

Idea on Code P0121
I'm not sure why code P0121 is being thrown, but I thought maybe when I was cleaning the EGR passages on the air intake manifold I had the throttle body still attached and maybe I did some damage to it? I didn't do anything crazy, I used oven cleaner maybe 10-15 times in the small passages with a small skinny wire brush in a large sink, I did get water all over the outside of the intake manifold and then drained it when I was done, and sat it on top of one of the heater vents in my house to help dry it, but I didn't think it would damage the throttle body, I left it on the intake since I didn't bother taking it off.

My friend has another one on a blown head gasket engine that I could take off and try, so I could take another throttle body part off and put it on mine and see if it clears up that code.

Summary
Does this seem logical, or something someone else has experienced? Is there something I am missing that is higher up from the coils that I might have missed that would be causing this? I am pretty sure the engine is okay based on how it runs, when it runs normally. I am very open to anyone's help or suggestions, as I would like to be able to start using this car again

 

So today I replaced the throttle body and it stopped the code P0121 from appearing not not the misfires and coil errors. So I replaced all the coils back to the originals and it runs like a dream. Thanks for everyone's suggestions and hopefully it could be of help to someone in the future. I've our about 25 miles on the car today and not a single hiccup since then.