I have started to have this problem over the past few months with my 2000 XJ. Every now and then while sitting at a stop light or drive through, my engine just cuts off. It has sputtered to a stop maybe twice and the other about 10 times has just stopped. The ECM isnt throwing any codes and it never does it while my foots on the gas (which it is to much). I am thinking its the TPS seeing how throttling keeps it from happening. I am just trying to see if anyone else out there has had this issue.

 

Could be as simple as the MAP sensor sticking (had that issue a while back) or also a failing IAC (idle air control) Pretty much rely on both of them for smooth idle, also, our jeeps have no egr system so that pretty well rules that out, and a faulty TPS would give the CEL and would stumble on acceleration. Hope this helps a bit

 

I have a link on how to test the MAP around here somewhere....

Here it is...
MAP Sensor Test Procedure