So when the CPS starts to act like an idiot, it makes the whole Jeep look like an idiot?
I'm going to change the spark plugs, will tell you back whats happening.

Meanwhile, I just checked the codes.. it is showing two now, 21 and a 45..
-21 Oxygen sensor signal doesn't change (stays at 4.3-4.5V). Probably bad oxygen sensor
While for the 45, I can't get a good explanation! Any one has an idea?

 

new fact: it only starts missing when the car is at about normal temperature. Like, in the morning i started it up, drove it around for a few kilometers. and then it started to misfire. shut it off, start again.. revs fine again.. but after one or two minutes, it starts to misfire again! Something is not like cooling down properly?

ignition coil could that be?

 

what about distributor cap and wires?

 

cap is good and clean.
Checked the plug wires in the dark.. Couldn't see any spark missing or glowing..etc
What is the best way to check the plug wires?
So it cannot be the ignition coil?

 

Could be. Grab some component cooler from radioshack and hit the coil with that a few times while it is misfiring and see if that makes a difference.

I dont think its the CPS in this case, although it could be the CPS harness. there was a TSB for whenever you replace the CPS to bypass the harness and splice straight into the wires going to the ecu.

 

TSB?

 

Technical Service Bulletin, they put these out for common problems.

 

Usually u just change them.
What i do is get the engine running with the misfiring and with a screwdriver point follow all the cables until u eventually grab some parasite sparks.