My car has been misfiring on essentially every cold start in the morning, after the RPM drops from about 1 to around 600. Last sunday it was misfiring so bad after I didn't drive it for a full day the day before that when I put it in reverse I was literally jerking back and forth, and when i was driving I could feel a trembling under my foot along with the car shaking. When it gets to this extent, the Check Engine light comes on and after driving for about 5min, the misfiring stops, and the check engine light clears itself right then and there. Now this morning after letting the car sit for about 11 hours, the same exact events of last sunday occurred where it would misfire terribly and cause a check engine light, I drove it around in hopes to rush it to my indy but the light cleared itself.
Everyday except for last Sunday and this morning, it misfires upon start up, but it's not bad enough to rock the whole car and cause the check engine light to come up. It's more of a subtle misfire around 600.
Last month, I had a sold Check Engine light that turned out to be "Cylinder 4 Misfire" I took it to the dealer, and they changed the HPFP and Low Pressure Fuel Sensor, that helped with my long cranks, but apparently not for the misfire.
The car has 45K, and I think the problem might be the fuel injectors? Any ideas?