cruiser54

Okay, here we go. There are 11 fasteners holding the intake and exhaust manifolds on. 9 bolts with thick washers under them and 2 studs with nuts.

Not trying to be harsh. It's a fact that all the bolts can be seen with a flashlight in about a minute. Start in the middle and work out toward each end. The job would be done in less time than has been spent asking how many bolts there are. Would it help if I went out to my shed and counted the number of threaded holes in the side of a 4.0 head?

Yes it is. Supplements the head to firewall ground which we know is crappy on a good day.

Wasn't busting your chops. But I believe once you look at it, it will be obvious, even if you're not mechanically inclined. This I do know: More Jeeps are actually fixed with tools and flashlights than with a keyboard and monitor.

It's pretty obvious. Got a flashlight? Start tightening them from the center bolts out to the ends with the engine cold.

Listen to the fool.

2wd should be easy. Be aware of the following before you actually start work on the oil pan gasket should you decide to buy: I'd be looking up above first. A leak at the back of the valve cover could produce the same symptoms. Don't jump on the RMS/oil pan gasket bandwagon just yet. Almost any oil leak on your 4.0 is gonna drip from the RMS area for 2 simple reasons. First off, the engine sits nose-up and oil will run back to that area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill". Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket have to be eliminated as possibilities first.

Actually, the ECU has a decent length harness on it. I would remove the ECU, unplug the connectors, spray out with electronics cleaner both the ECU side and harness side, and then tweak the female receptacles a skosh tighter with a small pick to ensure they grab the pins tightly.

I doubt it's the MAP sensor but it's quick and easy to change.... Fog, moisture, grounds? Oh my!!

Do everything one at a time so you end up knowing what it is. ECU connector refreshing fixed a buddy of mine's 88 and another guy on a forum had it fix his after they each went down a road similar to yours.

You haven't ever replaced the TPS, right?

That's a real possibility. Might have a bad spot in it. As to the grounds, ohming the grounds is great but it seems as if this gets worse with current load like when the lights are on. Therefore, the ground may say 0 ohms when you test it, but while putting a heavier load on that system with lights etc, they're inadequate. Heck, they were inadequate from the factory.

It's happened with them off; but most of the time yes. I'm running a 100amp Alt and a Optima redtop on the stock wiring harness. Ever refreshed your grounds and added a couple? Cleaned your C101 connector?

Headlights on when this happens?

That vacuum disconnect wouldn't affect your mileage by 1% of that much. The factory eliminated the disco in 91 or so. They wouldn't have done it if the EPA numbers were gonna go down. You still haven't adderessed the fact that if you haven't calibrated your speedo to account for the taller tires.

Have you ever checked your torque converter to flexplate bolts for tightness?

Auto or stick?

I ran some engine flush in the system this afternoon. Changed oil with fresh Rotella and a Wix filter. Ill run it for a bit, then Ill try the marvel mystery oil. Thanks for the input!! I have run Rotella oil in this vehicle for about 6-7k. I cannot imagine that running that oil would make this worse being its a diesel rated oil with detergents. BTW, 218k on this engine. Keep monitoring it through the oil filler hole with a flashlight. That Rotella is gonna help, not hurt. Keep in mind that you didn't see the inside of this engine BEFORE Rotella. I'll bet it was worse!!

The thermostatic valve that controls whether you get heated air from the exhaust manifold area or cold air from behind the grille?

How did you stick your finger into the IAC valve and open it? You talking EGR valve?

Not really. Please describe your symptoms and let's go that route.

Yes, it can and will.

I'm guessing..........

Be careful loosening that stuff up and it falling into the pan. Try running 1 quart of Marvel Mystery oil with 5 quarts of Rotella and a Wix filter for a bit, at least 1,500 miles. You can always check the progress by shining a light into the oil filler hole of the valve cover.