_____UPDATE_____
____please read___
-I replaced my positive wire to the relay/fuse center(passengerside fender behind battery).
-I also replaced the auto shutdown relay.
-I cleaned all existing groundwire terminals with a sanding bit on the dremel, retapped the threads on all groundwire bolt holes, and verified continuity on each ground wire.
-I used the same sanding bit and removed paint/metal on the terminals, body, engine block, intake manifold, and the underside and threads of all groundwire bolts.
-I added additional groundwires; One new groundwire is connected directly from the engineblock to the negative terminal on the battery. A second groundwire is connected from the negative terminal to the upper radiator support frame. I used the existing
braided groundwires' bolt location on the firewall for a third groundwire which I ran directly to the Intake manifold.
-I replaced my accel ignition coil(installed new Oct.2k8) with a new MSD coil. Part#8228.
-I used 2Gauge cablewire for all of the wires I replaced including the positive wire from the battery to the PDC relay box. This is not a 2Gauge stranded stereo wire, It was cut from the spool @ The Home Depot for $1.28/ft. utilizes individual solid copper cores and the sheathing is oil resistant.
-The 2Gauge terminal ends are solid copper, were also sanded, and continuity was verified from end-to-end.
I completed all of those items a little over 3 weeks ago and my XJ has not had even one stumble yet. I will not knock on wood because short of another cranksensor going bad, I have fixed the problems.
I personally believe the main problem was and more than likely IS the positive wire from battery to the relay/fuse box(PDC).
I believe everyone who owns an XJ with this positive to PDC wire setup should upgrade the entire cable regardless of the current problem you are experiencing & especially if your JeeP is ProblemFree!
-Since I replaced that tiny gauge wire, I have a stronger, more consistent reading on my battery gauge. The Idle is rock solid. Performance and throttle response are greater than before. I can run DELTA highbeams(H4's), foglights(H3's), rear window defrost, and other accessories without ever dropping below +/- 13Volts even while idling.
-The main reason I encourage you replace the wire is because when i opened the small cover that shields the terminal end on the PDC box, the wire, end, and PDC housing were covered in corrosion. the wire had corrosion almost the entire length of it! The outer sheathing was perfectly intact, I sliced down the side of the sheathing and there were scattered spots the copper wire was still pristine.
2Gauge wire here is NOT overkill; however it is extremely hard to work with in such a tight and fixed location. I say fixed because the cable has an L shaped end on it with two holes and only one nut holds it to the box. I strongly suggest using an impact driver to remove the nut especially if the corrosion is present!!!
Use of a wrench, cordless drill, socket/ratchet will cause damage to the box/nut/stud/or worse.
I reused the straight section of the L bracket end, and mounted it under the copper terminal end of the new 2Gauge wire. Remembering to mock this up many times including after the box is snapped back down in its fixed position I started the bends.
Once perfect during mockup then you will know how much electrical tape or shrinktube to use. Then double it! Remember this is a positive source carrying hundrends of amperage, if anything metal of the vehicle touches it, It will be bad, very very BAD!
Adam