First off the jeep was rolled and I rebuilt it. It's an 88' with the 4.0L and 5 speed. The motor keeps backing up, if it idles for awhile it blows more black smoke than an old diesel. I finally deemed it road worthy...enough and it burned the whole tank of fuel in a 100 miles!!
Any Ideas? Are there sensors that I am not aware of? Timing?

P.S. I changed spark plugs already
Thanks

 

Finish the tuneup with plug wires, distributor cap, rotor. Gotta have a solid secondary ignition system.

If no change after above, I'd start with fuel pressure testing. For an 88, you should have 31 psi at idle. Then disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approx. 39 psi. Be sure that the vacuum line is pulling GOOD vacuum and if the vacuum line is wet, that indicates a blown diaphragm in the fuel pressure regulator.

After that, start testing sensors. Here is a link to testing many things on your 88. It is a good bookmark.

Good luck.

http://www.lunghd.com/Tech_Articles/...iagnostics.htm

 

I'll get started on those thanks