Only happens at idle, runs smooth down the road, reader said up stream 02,changed it, fixed nothing, changed fuel filter, pluggs and air filter, now getting all 4 misfiring, no 02 (so far) but now P0450. Can anyone set me on the right path to get this figured out?
Thanks

 

Any coolant temp sensor misreads? i was misfiring like a monster until i pulled that code, and replaced it, now just idle low, and sound like a tractor.

 

For me it was replacing both ignition coils. Also, make sure the wires to the coils are fully seated onto the round pins inside the coils. The plastic holder for the wires lets them back away from the coils. I had to push the wires further into the plastic holder to seat them fully into the coils.

The P0450 is Evap code? Isn't that from running the car with the gas cap loose?