Trying to get to the root cause or at least some ideas. My sisters old 2000 WJ will randomly die at traffic lights. no sputtering or anything just dead. Fires right back up when it happens. any one got ideas or what to look for.

4.0L I6 with an np242 (one with full time 4wd)

 

Not sure about the WJ, but if its like my current issues with the XJ, maybe an idle air controller? Check the IAC.

 

Dirty IAC, worn out distributor cap, crank position sensor, fuel pump.
Are any codes showing?

 

no codes has fresh CPS with in 15k no distributor ($$$$ coil packs)

I drove it a little more the other day and in first gear at idle pointing down hill it idles at like 500 or so.