Have you tried increasing the idle speed when it is warmed up?
There is an "Idle Adjustment Screw" and a "High Idle Adjustment Screw" on the factory carbs..........I believe you have a 1986 B2000 truck and it still has the 2.0 engine.....right?
Does the truck idle real high when you first start it in the morning? If so, you can lower that a little by using the "High Idle Adjustment Screw" but it will have no effect if the choke is not engaged, so make that adjustment when you first crank it up in the morning for the best results.
Is the yellow (with a blue stripe) wire for the choke (connected to the choke heater on the carb) plugged into the back of the alternator as it is supposed to be?