well i need some help..

the car is an old postal wagon, right hand drive, 2.2, automatic, awd. 186k.

 

it only does this intermittently and is drivin me nuts. You'll be driving along, then it starts missing bad, check engine light comes on, won't go above 45mph with your foot in it. then all of a sudden it clears up and is fine for awhile.

 

the cars had a new coil pack, wires, plugs, pcv, fuel filter, etc put on it.

the check engine code is either random misfire or cyl #3 misfire. can't seem to figure out whts causing this.

 

any ideas?

Sounds ignition related.

 

I would probably start by cleaning the connectors to the coil and ignitor really well with contact cleaner and a brush, then apply some dielectric grease. Look for broken/loose wires on these connectors. Check your grounds and battery cables. Could be a bad ignitor.

 

It might be very telling to look at the O2 sensor voltage when the problem occurs. If it goes low (0.1V - lean), you have a fuel delivery problem, if it goes high (0.9V - rich), you have an ignition problem.