I can't solve my misfire problems! Code reader is showing multiple/random misfires, misfire on 2, 4, 5, and 6. So far we've put a different head on it (mine was cracked), new plugs and wires, a clean cap and rotor( used), a coil and injectors(both off the same engine). After changing the injectors it ran smoothly and had substantially more power, but on the way home from work it started skipping again. Also it only does it at idle, or under 1000rpm.
Any suggestions?
97 xj, I6, rwd.

 

I chased a hot idle/misfire problem for a couple of months. I had replaced most of the ignition components over the previous year including the coil (with Echlin from NAPA). Turned out to be the coil. Only missed at idle, but gave me plenty of misfire codes. I put the original MOPAR one back in that I had replaced and everything was good from there.

 

Gf was driving home yesterday, xj started sputtering every time she slowed down and eventually dying instead of idling. She made it home ok though. I got home and scanned for new codes. Got 4 instead of 8 this time. Ignition coil primary/secondary, misfire on 4, and the 2 nss codes. Decided to pull the coil back off for a visual inspection, it's cracked all to hell. Bought a new one, installed, no change. Checked for spark to plug 4. I have spark. But no change when pulling the wire off with engine running. Moved the harness around from pcm to coil, it died immediately. Wiggled around a little more. Restarted, no mis, wiggled wires, died... Could it be as simple as cutting the plug off at a jy and splicing it into mine?

 

Yes, but you need a good mechanical connection between the wires. If you get a bad solder, the resistance is going to increase which might cause issues.
Might be more worthwhile to pull the whole harness and replace it with one from the JY

 

 

I've checked the wires as far back as I can see, saw no issues, it is changing the idle only when I move the two right at the plug.

Also, no jy near me has the harness, the plug or anything so they say. One said they have it but won't sell it because then they can't start the engine. Options?