need a few ideas

[mastertech]

Have this car comming into the shop in a few days that has a problem that seems that no one can put a finger on. Its a 2002 dodge intrepid with a 2.7 engine, when you first start car will run fine after appx 30-40 sec it will missfire for appx 2 min the go away. checked it on scan tool i have miss fires on cylinders 1 3 and 5. Now if you drive it is fine, untill you shut off for 20-30 min the starts all over. It will turn on the check engine light.

So far the plugs have been changed, compression checked (within specs), coils been swaped to other side of engine (miss fire stayed on 1 3 5 ) Fule ingectors cleaned and tested, have replaced the upper intake gaskets/seals( they are rubber d rings) Have also replaced the lower intake manifold, it is plastic with rubber seals . I also believe that somewhere along the line someone replaced the o2 sensors. They have also replaced the cam sensor.

This is A overhead cam engine with chains driving the cams. Because the engine runs so good i done believe the chains have jumped, if it did this is a bend the valve engine, but i havent put that out yet. I havent work on this yet just kinda help out the guy in shop but when anything comes back for the 4th time i end up with it(crap floats down hill). I dont think that there is any coolant loss, and the owner hasent complained of any oil useage either.

Just trying to get ideas I have talked to the guys at chrysler tech they have no idea what to look for. Any idea would be great no matter how off the wall it is I'll try anything at this point. Oh yeah i believe it has appx 100k on it it is well manitaned we have serviced this car since new. If we get this one fixed have a 2010 advenger that wont turn over when the temp gets below 40. been dealing with that one since new, but that one is for later.

[mastertech]

forgot also replace the pcm and checked the wiring to each of the coils both when the engine cold and hot both side to compare and both had same resistance and voltage