I have a 2010 Prius and I'm getting a check engine with Cylinder 4 missfire. Head gasket has been replaced and the engine never goes down so don't think it's that. I replaced the EGR (with toyota new) cleaned the intake and all the pipes. Replaced the spark plugs with new one step hotter plug. Swapped coils 3 and 4. Never see a missfire driving but after a couple weeks check engine light comes on. Anything to try next?
