This issue with my Prius only happens sometimes at first start. When it does it is very upsetting. It feels and sounds like the motor is going to fall out. The check engine light appears and codes for misfiring P0302 & P0304 this time around. The car is drivable. It stops after 10+ seconds and the car fines as usual. The first time I had it towed to the shop the codes were multiple and random. The mechanic changed the 12v battery and cleared codes. He never heard the vehicle symptoms in person. I drove the car home 100 miles, the next day it did it again. Now the codes are 302 & 304 as specified above. No one seems to know exactly what it is. Some say it is plugs and coil, some say blown head gasket. There is no indication of blown head gasket.

I am finding online many complaints of the same problem with other Prius owners. Now my car is sitting because I am afraid to have it towed all the way back for no remedy. The diagnostic done shows nothing. Anyone else having this issue please comment. I am so upset. I love my Prius and do not want to have to park it if there is a solution someone knows about. The video I have attached is not my car but just an example of the sound it makes when I first start it and only happens sometimes.