So I got tired of my 03 recently, especially with all the bull**** it's put me through with the coolant leaks and the IAC issues. So I went out and picked up a new car today. Got an 04 Intimidator with the L67. The motor only has 55k miles on it, was replaced with a new Jasper engine (checked with the company, it's legit). Only problem is that it's misfiring in cylinder 6 (throwing P0306), but only when idling. Drove it around an hour and a half up 95, and it ran perfectly. Not a single problem. Doesn't even have the misfire when at low RPMs, just when it's idle.

I did a **** ton of reading up on misfires before I bought it (got it for pretty damn cheap). Saw that it's usually caused by coil pack/spark plug issues, fuel injection, or a vacuum leak. I highly doubt it's a vacuum leak considering it's running perfectly when it's being driven, only at idle. Same with the coil pack/spark plug.

I'm gonna check the coil pack, the plug, and the wire tomorrow, since it's easy to check. Although the 6-3 coil pack is in the 2-5 pack spot (in the middle), I doubt it's wired like that too, because that would cause all 4 to misfire right? I'm leaning more towards a fuel injector. If I am able to rule out coil pack, spark plug, and plug wire, do you guys think I should yank the fuel rail off and replace the fuel injector? Or even just use some contact cleaner between the injector and the plug going to it? Just hoping one of you guys dealt with something similar and can give me some advice on this one.

 

Sounds like your on the right track. Check the plug and if it looks questionable.change it ,if the wires are original change them. Even if its low mileage that is the second engine and might have gotten damaged during swap. Coil packs are interchangeable so that's not a issue and I would ohm the injector before blowing a new one at it compare the injector to cylinder 2 or 4 . Good luck