Transplanted 4.0 keeps dyeing

I have a motor, wiring harness, and computer from an 87 Cherokee that I transplanted into a carburated truck. I kept the wiring harness intact. I just spliced the ignition switch wire(carburated truck) to the red and the yellow wires on the computer wiring harness(87). Then wired in the fuel pump and starter. I drove it for a few days on short 10 mile or less trips and it worked fine. Then I tried to drive it about 50 miles and it died at a stop light. When I tried to start it it will start but then just sputters and idles at about 500 RPM. Throttle position makes no difference. You can floor it and it will still just sputter at about 500 RPM. I let the Jeep sit and started and ran fine for a while. Now it just randomly has this issue. It did die once and wouldn't start at all. When it did this I checked and it had no spark. This time I also found the crank position sensor shorting on the exhaust. I fixed this issue and it has not died since. I don't know if this is related.

Please help I'm pulling my hair out!!:doh:

Yes, a shorted CPS sensor will cause it to die with no spark.

I fixed the CPS and it will still randomly die. Then when I restart it will only sputter at about 500 RPM. You can floor it and it will still just sit there and sputter at about 500 RPM. If I let it set for a while it will restart and run fine for a while.

I've spent way too much time sitting and waiting on the side of the road this week.

lol

I agree that cps is most likely. but if that is not it. i would take the multimeter and check out the tps. I would also go through all the grounds. and make sure that you are using something beefier for the block to firewall ground than the flat little ribbon that came stock on renix era rigs. i am using 00 welding cable with lugs on both ends. Good grounds mke everything on a renix work better.

and the multimeter is your best friend now.