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I'm going to assume this is a fuel issue. But it’s like there’s no end to it. The truck cranks and Idles fine. As soon as you get on the road, it skipping, sputtering, and barely get 30mph out of her. First it was a fuel injector. I found I had a dead injector by pulling the wires to each listening for a change in the engine. Ok replaced it, ran great for 2 days. Then same sh*t again. Seems it was a plug, so replaced plugs and wires, again , ran good for 2 days and back to skipping. I found the intake and exhaust manifold bolts were finger tight. Replaced the gasket, And torqued everything down. You guessed it…….2 days. Then another injector, got another 2 days. Anyone else noticed the pattern here? Yea , I’m losing my patience. Fuel ballist resistor or whatever it’s called seemed to have corroded plugs, clipped cleaned and replaced. 2 days again……..over and over. The fuel pump sounds to be working fine. So wtf is going on? Also I replaced the crank sensor and I got a loud whistle almost like it has a turbo on it now.

Hey all, new to the forum, been using this and jeepforum for the past 2 months to keep my MJ up and running. Quick history on the MJ then I'll give ya the dirty dirty: Swapped for the MJ (4x4, 4.0L, Big Ton, with 5-spd) about the end of August down in NOLA. Exhaust manifold wasn't connected, but otherwise it ran great. Drove around town like a bandit then left a week later to Alanta with no issues other than gassing myself in slow traffic (also, possible hearing loss). In Atlanta, bought nuts and reconnected exhaust. Much quieter, ran good for another tank of gas (300 miles maybe less) started idling rough. Pulled plugs (they were shot, maybe even original to the jeep). Replaced with Autolite 985 copper core (gapped to .035" I'm pretty sure). Fixed idle issue. Loaded up and headed back to NOLA. Left mid afternoon, got a hesitation or two along the way, could have been a bump in the road. I get about to the La. state line (about 11pm) and the truck starts misfiring and surging erratically. Hold the throttle and try to cruise at any speed/gear/rpm and it bucks and fights. Under hard acceleration the problem is there but much less pronounced. Let off the throttle and the issue seems to go away (truck isn't shaking anymore, hard to tell over hwy noise). No CEL at any time. Limp into NOLA and over next 3 weeks: Replaced Fuel filter- no change Tested fuel rail pressure and flow rate- ~31psi and 39psi with regulator connected/disconnected. With return pinched off flowing close to 2l/min (filled 500ml bottle in 13 seconds). Pulled spark plug wires and checked for resistance...all were similar with longer wires slightly higher than shorter wires. Cleaned ends and reattached (all done one at a time then double checked for order) - no change in symptoms Pulled old O2 sensor and bench tested. Readings very erratic. Order new Standard SG1829, bench tested it to compare readings. New one cycles as expected from .1-1.0A in flame. Installed new O2 sensor and problem appears to be fixed. Test drives, no bucking, no skipping. Next day leave NOLA around 4pm, drives great for first 150 miles. Pouring rain, temps drop and from around Lake Charles to Victoria, Texas the misfires are as bad as ever. Pulled over several times and disconnected/reconnected O2 sensor trying to get the ECU to run the motor rich, used ether to locate at least one vacuum leak (repaired with electrical tape), tried plugging vacuum lines, looked for spark leaks, wiggled wires and lines, dumped in a bottle of B12 Chemtool and 89 Octane out of desperation, nothing. If driven at high rpm the misfire is dealable but anything below 2000 rpm I'm afraid I'm going to blow the bottom end of the motor out unless I'm accelerating WOT. Then, after taking a nap in Victoria I wake up this morning, fight the misfire for about an hour and after the sun comes out and it's 84 outside, the truck drives with no issues. I can't get it to misfire, even by lugging the engine under 1200 rpm. I've got a cap/rotor/wire set on order, bought PCV(CCV, little plastic elbow thingys) to fix my blow by, and some new vacuum lines just as maintenance items on this thing. If these don't fix it, does anyone else have any other ideas? I've read about a coolant temp sensor maybe? The fact that it seems to drive ok in 80*F and hotter has me a little confused. Posting this on two separate forums....I'm not looking to parts swap and guess. If you can give me an idea and a possible troubleshooting (or hell steps even!) I would rather do that than throw money away.