p219a Intake Manifold?

Hi Everyone,

So, in a couple days, i think i'll be taking on the project of cleaning the intake manifold (and EGR pipe, and maybe the throttle body). Here's how i've gotten to this point:

I noticed a slight shuddering/shaking/sputtering a few weeks back, and it was only at certain RPMs. If i pushed the gas down to really accelerate, it would run fine, and the same for if it was just coasting downhill or a few slight amount of stepping on the gas. A few days after, the engine light came on it had a code of p219a, air/fuel ratio imbalance on bank 1. I was due for an oil change anyway, so i brought it in to the dealer and they did the oil change. Amazingly, i forgot to tell them about the shuddering. Anyway, after the oil change, there was no improvement in the shuddering. I brought it back to the dealer a few days later and they said they'd have to run a full engine diagnostic and that it would take a few hours, so i had to reschedule for another day. After that, i tried two bottles of fuel injector cleaner (one bottle per full tank of gas), and then i replaced the spark plugs (they probably had about 80k miles). None of these things resolved the shuddering, and the shuddering was getting worse over time. I brought it in to the dealer and they ran a compression test. The cylinders had 215, 205, 209, and 205 psi. According to the notes on the service report, these are all within specification range. The dealer said that the likely problem is a bad engine valve and that i'd have to replace the engine, and that is a game over for this car.

I searched on here for a bit and on google, and i found a couple people describing this exact same symptoms and that cleaning the intake manifold solved the problem. A few more details: 2014 Prius Two, 212+K miles on it, shuddering only happens when using the gas engine, never on the battery (obviously). My mpgs haven't been reduced as far as i can tell, but maybe the fuel injector cleaner helped with the mpgs for those tanks. No knocking or pinging, just shakes badly as certain rpms, and it seems to get worse the warmer the car gets.

So, just wondering what everyone thinks. Is cleaning the intake manifold a good chance of fixing this? I've already watched the video on the the cleaning process, so i know what's involved. The car has been great prior to this, and i'm hoping i can save it and get to last another 100k. Also, since this issue has been ongoing for a few weeks, have i caused damage to the engine itself?

Thanks for any help!!!

Owen

 

Cleaning the EGR cooler would add on a good amount of time, and i don't really have all day to work on the car. I suppose i can clean the opening after i take off the EGR pipe. And, people seem split on whether to replace the PCV Valve. It seems logical since i will have such easy access to it, right?