ZJ 5.9 Woes

[jeepsrock]

My friend has a 98 zj with the 5.9 and recently performed a tune up on it. The tune up consisted of Replacing the plugs, cap+rotor, wires, oil+filter, tranny fluid+filter. After performing the maintenance, the jeep idled really bad and was missing/stumbling harshly at all RPM. I eventually found out he used NGK plugs and promptly recommended he switch them to champion plugs. After switching them the jeep ran fine for an hour or so and i drove it an everything seemed dandy. The next day it starting acting the same way ???
I went back and put a timing/inductance gun on all the plug wires and it seemed that plugs 4 & 8 (passenger side) where lighting up funny. We replaced the wires again and its still acting weird. A quick look up on the net yielded a TSB by jeep for all 5.9s regarding the routing of the plug wires. I tried this with no change. Additionally i unplugged most sensors and cleaned the connectors.

I am a bit lost guys, any ideas ?

UPDATE:
We checked the wires and the corresponding firing order and they are fine aswell as bosch brand.
Secondly we changed the ignition coil, with no improvement and checked plug gaps (champion .040 gap).
I checked all grounds and cleaned them aswell as the battery terminals.
Cap and Rotor have been replaced again with brass units.

Any further ideas or suggestions.


THanks
pete

[jeepsrock]

no ideas ?
I am going crazy on this ?

pete

[Madd Ramm]

Fuel issues, computer issues?

Hook up a computer and find out.

[jeepsrock]

The check engine light is not on and a connected scanner shows no codes at all.
I am not really sure what to do next...
Pete