eh... your heads are going to need to come off. IIRC there is a tsb on 05 and 06 libertys with the 3.7 reguarding replacing and lapping in new intake valves due to carbon buildup. You could try a solid decarb, get the motor flamin hot, drive around in 2nd with your rpms higher (3500-4500) once you have accomplished the hot engine then you want to use your seafoam or mopar combustion chamber cleaner you want to suck it in at a decent pace so as to not burn it all off as your doing it, then shut the vehicle off as soon as your can is out. Let it sit overnight then start it up and take it out for another hard drive. Then inspect for results. The last one I saw doing this the head had to come off (service contract only covers whats broken, but if you were to do it I would suggest doing both while you have it torn apart).
DATE: August 19, 2006
Engine Misfire At Idle
This bulletin involves installing revised intake valve locks and intake valves.
2005 - 2006 (KJ) Liberty/Cherokee (International Markets)2005 - 2006 (ND) Dakota
NOTE :This bulletin applies to vehicles equipped with a 3.7L engine (sales code EKG).
The customer may experience occasional engine misfire at idle (rough idle). The malfunction indicator lamp may illuminate for single or multiple cylinder misfire.