So i have been having a misfire problem lately. It will only misfire at idle. If i give it gas it goes away. Same if im going down the highway and let off the gas it will not misfire. It also only happen occasionally. It happened one time for a few days and then out of no where didnt happen for another 2 weeks. I replaced the spark plugs and wires 1k miles ago. It is cylinder number 4. I was thinking of replacing the coil pack next or maybe the fuel injector for that cylinder. Any other ideas from anyone are welcome. Its a 99 3.0 with 180k mlies. Thank you for the help.

 

Is there a CEL and a code?

 

Yes the CEL comes on but then goes away along with the misfire then comes back every some often. Cant remember the code but it was a misfire code on cylinder 4.

 

It's only been doing this since the plug and wire change, or did you change the plugs and wires because of the misfire?

 

Your best bet is to do a compression test on all 6 cylinders
Pull out all spark plugs first and then test compression in each cylinder, WRITE IT DOWN

Reason to do this FIRST is it will save you time and MONEY
You can not fix a compression issue with new parts installed on the outside of the engine, so best not to waste money until you KNOW its not a compression issue

Compression is related to "time" the faster the piston is moving the less compression is lost thru valve and ring seals, so misfire at idle that goes away at higher RPMs(faster piston speed) could be a compression issue