i have a 1989 jeep wagoneer limited. it is a cherokee body style with the 4.0 staight 6 fuel injected. a few weeks back i drove it to walmart and when i got back it wouldn't start. So i had to tow it home. i had the fuel pump replaced a few months back. i had the ignition coil check and it failed also the ignition module failed so i replaced them. I pulled the distributer out and had it tested. The barring where going out so i replaced it as well. Also the crack shaft position sensor was burned and i think shorted out when it rubbed the manifold so i replaced it too. i have it in time and it starts up and runs but when you give it gas it starts to jerk the car but when you let off it idles smooth again. i had the fuel pressure checked and it passed. i had replaced the throttle position sensor and fuel pressure sensor to be sure and it still does the same. i had found that the cruise control computer(yellow AMC box under the steering wheel) had a burned resister(may that cause this, does the cruise control effect how the car runs?) if anyone could help me with this i would greatly appreciate it.

P.s. also it has a new rebuilt trans it it. it doesn't have a blown head gasket. also the timing chain isn't broken or warn out(had tested it). i was wondering if anyone knew what happens if the idle position sensor goes out?( i was told that the opposite problem my jeep has would happen. it would not idle well but it would accelerate fine. also how do you run a code tester on this wagoneer? it doesn't have a plug in under the dash. where could i get the codes if i could. all the books i have skip 1987-1990 jeeps. on codes.