I recently bought a 1989 YJ with 4.2. It would never idle and stalled out at every stop. I went through the vac hoses and replaced some, but no real help. Then I started spraying carb cleaner around the carb and noticed it was leaking big time around the throttle shaft (which I was kinda expecting after reading the many posts here about the POS carb).
Anyways, I knew a basic rebuild kit would not help, so I took it in to a carb shop locally here in SoCal. They rebuilt it with some 'updates' to account for the newer fuel blends and also put in brass bushings on the throttle shaft.
Installed the carb, set the idle, set the mixture screws and voila!!
Engine starts with barely a crank, and idles like a Lexus! If anyone is interested, the place is CA Carburetor. They don't have exchange units, and will need your carb, but they do a fantastic job, and I highly recommend them.
California Carburetor & Fuel Injection in Lawndale,* CA *|*4921 Marine Avenue,* Lawndale,* CA