Have Jeep liberty with a misfire on cyl 2-3, also have codes po0303, po455, po432 and p1281. I took to shop and obtained a tune up, no help. brought home checked compression, coils, fuel injectors, plugs, cleared codes and inspected vac sys. The mechanic did move coils around but prob still persisted on same cyl. My friend and myself resolved the issue by, re- gaping plugs, removed the connector pins from housing that plugs into coil, these were cleaned and adjusted to fit snug, also applied a little electrical grease and reasymbled. the coils did show spark but were replaced, compression withing normal limits for the 3.7 ( normal is 170-225 lbs well thats what i was told anyway). the plugs were all out of gap up to .045 ( .040 normal ). The shop charged me 150. no results. i spent around 50. Results car fixed problem resolved. hope this helps.