Car keeps misfiring
About 4 months ago check engine light came on and the
car had a misfire. Took it to mechanic. Back ignition coils
bad. Got them swapped. Car fixed. Month and a half later
same problem. Misfire not as bad, but still there. He
swapped out the EGR. Fixed again. Now 2 months later
again and same problem. Car runs fine for about 30min.
Anything after that it starts to misfire. Again. What can I do
to get this problem fixed???