1990 Isuzu Pickup Question: Engine dies at stops

Did you end up finding out what was causing the stalling problem?

There ours is having the same issue. It was suggested tome today to get carb. Spray and run the engine whe spraying the spray in small areas. If spraying in a certain region raises you RPMs then you have an air leak. Won't be your fuel filter if you motor runs fine at higher speeds. Sounds like your engine is taking in extra air. I will let you know if this helps us find a potential leak and solves our trouble.

I am guessing you have the vacuum line assembly on this (aka the octopus). I have to regularly replace vacuum lines in my 1993 pickup, as they split and leak within a few years, and there are a lot of them. As they are all the same size, I keep a spool of the tubing and cut it to length. It seems every time I check, I find more than one with a leak. These leaks make for a very erratic idle and make it likely to die or diesel.
I do keep my idle slightly higher because of the carburetor issues, and I adjust it with weather changes to keep it stable but as low as possible
If you aren't familiar with the idle screw, it's very easy to adjust. It's literally a screw on the underside of the carburetor cover; all you need is a screwdriver. The first time you look for it, it might be easier to find if you take off the lid and housing that hold your air filter, as it is under them. Look on the passenger side of the carburetor for a flat head screw next to a small tension spring. While the engine is running, turn the screw slightly to raise or lower the idle. (Always be careful working with a running engine!)