surging idle after transmission swap (RENIX)

So I just recently did a tranny swap to gain 4wd on my jeep. Everything went well and the jeep drives good. But today I noticed that at stoplights the jeep would idle low and surge back up occasionally. Was wondering if anyone has an idea of what might cause this. Jeep is a 1990 4.0L AW4 auto. Only thing I can think of is maybe the CPS because I cleaned it off before putting it on the new trans. But wouldnt that cause a no crank instead of surging idle?

Yeah, I don't think its the CPS. More likley a vacuum leak or a TPS sensor on the TB. IAC valve could be another culprit.

CPS(crankshaft pos sensor) can cause stuttering and/or stalling out and/or not restarting.... if it's grounded out from sitting ontop of the exhaust manifold after a sloppy engine/trans swap... ask me how i know. after i pulled it off the ekimani, due to budget reasons we didnt change it out... it seemed to run fine, and it did... for about 6-8 months... fallowed by high speed stalling and other really weird stuff.... it wouldnt drive with the headlights on (at night), but would drive in basically limp mode during the day (no lights). the only thing we did was change out the cps, and its back to runnin fine...

all this was also on a 1990 renix 4.0, but a 5speed.

first things first, check for chaffing and/or melting of the CPS wire....

Double check that the hose to the MAP didn't get disco'd. The hose goes to the bottom hole on the throttle body.

It just occurred to me that I never readjusted the TV cable. I dont think this is the problem but, thought Id mention it to see what you guys think. I will check the CPS and the MAP once I get home since Im at work now.

CPS wire is fine from what I can tell and was routed correctly. The MAP is also connected just fine. I will get my multimeter and test the CPS tomorrow though to make sure its working good still.

I ohm the CPS today and confirmed it was toast. I replaced it and now it runs good again. Thanks,

good to hear you got it working.