runns rough when hot

ok so say i have drivin for like 2 hours i go and turn my truck off and then i go and start it up like 10mins later it starts but sounds like it is runiing on like 5 cylinders. then i drive it for about 5 mins and it comes out of it and runs fine. i have a 90 xj 4.0 auto anyone have a clue what it might be?

My 2000 does this, check out this link. The TSB says it's for 99+, but maybe it's the same deal on yours?

1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK
Date: 09/05/03 (supercedes 1802702 dated 09/06/02)

Model Year(s): 1999-2004

Description: NOTE: This bulletin applies to vehicles equipped with a 4.0L engine. This bulletin involves the installation of a fuel injector insulator sleeve.

Details: Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a prior 10 to 20 minute heat soak in hot ambient conditions of approximately 32 C (90ºF) or higher. This condition may be consistent with short city stop-and-go driving trips and can be aggravated by the use of fuel with a high ethanol content. Depending upon various conditions a MIL may occur due to DTC P0303 - Cylinder #3 Misfire.

This condition may be caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector #3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder #3 until the fuel vapor is cleared of injector #3. The insulator sleeve lowers the injector #3 temperature to a point below which the fuel will not normally vaporize.

If vehicle exhibits a rough idle, and if a misfire of cylinder #3 is observed following a 10 to 20 minute hot soak, perform the Repair Procedure.

Parts required:
56028371AA Ignition Wire Shield

Repair procedure:
1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length. See diagram.
2. Install one sleeve around injector #3, with the slit on the upward facing side of the injector. Install the other sleeve with the slit on the downward facing side of the injector.
3. Confirm sleeve is flush to intake manifold surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o'clock position (from driver’s side of vehicle).

Another possibility is a poor connection, or a bad splice in the wiring harness. As I've reported a few times here in the past, my stepson's 93 had the latter problem, and it was a real bear to track down, though ridiculously easy to fix. It would only happen when it warmed up, especially after parking and restarting. In this case it was a bad splice inside the injector wiring harness, on the postive (common) line from the coil. Basically, the problem is that a slightly resistive splice or other point of contact will, because of its resistance, make heat, and heat in its turn increases resistance, etc. etc. round and round. So you're driving along with a little undocumented resistor in the wire, it heats up, adds more resistance, and at some point, though it doesn't exactly shut off, it gets just high enough to prevent one injector from firing. It could also be a similar problem in the injector itself as its own coil heats up. I've never had that with an injector, but I've had it often in the past with fuel cutoff solenoids on carburetors and the like. The first thing I'd try is just to clean up all the plugs and connections in sight, including (perhaps especially) the ones on the injectors.

If it's an injector wire or an injector, you might be able to track it down by driving until the problem occurs. Then unplug each injector in turn. I'm not exactly sure how the REnix system will handle this, but on the Chrysler system, the engine will slow a moment, then return to idle speed. If you pull one and the engine does not first bog down a bit, you've found a dead injector. The next step is to swap the connector between that one and the nearest adjacent one, and repeat the test. If the problem follows the plug, it must be the wiring. If it follows the injector, it's the injector. If you have the kind of injector harness plugs with a stiff little spring in them, you might want to remove all six before going on your test run. The plugs will be much easier to pull in a hurry, but they won't fall off.

well thanks guys for the input i will try both ideas the only other question i ask is to dbxj the diagram that they talk of do you know where that is or did you do this to your jeep and i could have a picture?