2007 Prius just turned off and won't start again.

Hey guys, please bare with me as I explain what happened and hopefully someone will know what my issue/s is/are. My car has 226,000 miles on it. About a month and a half ago, I changed the plugs. Once I got to the last plug, on the right, it was soaked in oil. I assumed that it could be a valve seal or a valve cover gasket, neither of which I would be able to change. A few weeks passed and my check engine light came on. I took it to Autozone and put the code checker on it. Here are the numbers that came up: P0303, P0300, P0301, P0303. So, an ignition coil. I was looking into buying one. A few days passed and as I waited outside the bank for my friend, car running, it just shut down. It turned off, but the dash lights were still on, with the red triangle and the circle with parenthesis around it. I had it towed to my local shop. My guy is good, but does not specialize in Toyotas. He ran the codes, different ones came up, he cleared them. The car ran, but then shut off again. Re-ran the codes, different ones showed up. Again, cleared them, it ran and stopped again. The only codes that he said were consistent where the ones showing cylinder 3 misfire. He changed the ignition coil and spark plugs (no oil on any of them), also changed the oil. It started, no lights, they test drove it twice with no problems. He called and said it was ready for pickup. I picked it up, drove straight home (about 8 miles), parked it. Two hrs. later I went out to go somewhere. I started it, immediately, the check engine light started flashing, about 15 seconds of flashing, then it stayed on. I drove right to Autozone and plugged in the tester and bam, P0303, ignition coil. The girl said to just give it a little time. I pulled out of Autozone and was about a 1/2 mile away and all the warning lights came back on, just like before. The car was in drive, as I was at a stop light, still running though. I turned around, went straight home and turned it off. I tried to start it and nothing, just the warning lights. Would anyone have any idea what in the world could be causing this??? I have no codes to pass on. Is this a sigh of battery problems?? Thanks for reading and any input.

 

Hi Ed, neither the red triangle nor the check engine light has come on due to low oil. I was check the oil regularly. The 12v battery is on about a year and a half old.