My 1989 xj has been having low idle problems lately. It would die, when run for about 30 seconds, due to it idling so low. We bent the flap that is connected to the throttle cable so that it would idle a little higher. Now it will not die immediately, but when in gear, ESPECIALLY reverse, it idles super low and it died last night, because of this.

MAP sensor has been changed, IAT has been cleaned, TPS was adjusted to spec., but I can't seem to be able to fix this. (engine was recently rebuilt too) I'm sure most of you are thinking O2 sensor, but I'm thinking its more about it being in gear and then dieng. I think fuel pressure is ruled out, because it is fine when in park or neutral. Help please!!!

 

You got a vacuum leak somewhere. Not a very bad one but, just enough of one to cause this low idle dying problem.

 

Buck, I added this to a thread titled blue vacuum hose, but this might actually make sense. I know that there is a blue, red, yellow and green vacuum line going down to the t-case control, and I have them there, but then near the starter, I have these metal lines coming down by the starter, but they just kind of end opened up like there should be hoses on them.
These pics are just to the left of the starter if facing towards the back of the car.

 

Any clue as to why it only dies in gear though? I just changed the vacuum lines that were all messed up by the PO to the correct stock vacuum set up that run from the air box, to the manifold and that area.

 

If you believe those lines to be vacuum lines, put your finger over the end of each one with the jeep running. If you feel them sucking (vacuum). If they don't directly operate anything, cap them off and see how your Jeep runs then. Any open vacuum line is gonna cause you problems with how your motor runs. Hopefully this will fix your problem.

 

Alright I checked them with the jeep running, and the bottom one (As I remember) had vacuum that I could feel, the others did not though, unless It was too weak to feel. When I plugged them up I didn't see any noticable difference??? I just want to know where the hell these are supposed to connect to, because I'm sure it is effecting something! (transmission is my best guess)