Bad idle?

I have a 86 B2000, the darn thing will run and idle good till she gets warm, then it will start to spit and studder. Whast could be doing this?

Vacuum leak somewhere.plug wire not seated properly.plugged up CAT.BJ

no cat, plugs are seating good, probably the vacuums

Spray some starter fluid around the carb with the air cleaner on and tightened down. If it revs up or changes in idle then there is a leak somewhere. If not try cleaning the carb by spraying some carb cleaner down inside it while its running.

Worse case rebuild the carb. I was having problems with mine and tried everything. I eventually got a rebuild kit and rebuilt it. It took about 8 hours total to rebuild it, but it ran perfectly when I put it all back together and started it up. I could rebuild another one in half the time now. I took my time before and followed the instruction slowly and it was easier than I thought it would be.