'87 D100 - 318 with Holley Carb (don't know the model, assuming it is factory equipment). Truck starts and runs fine but the choke seems to take a really long time to come off completely. It seems to hang up on the lowest position until waaaay after the engine is warmed. I believe there is a thermostat of sorts that controls the choke position by a push rod. Is the thermostat replaceable? can I get one with a different temperature setting? or is there an easier way to fix this? I have turned the high idle screw back as far as I can to make the truck drivable, but the gas mileage is terrible with the choke on all the time. Any suggestions?

 

I seem to remember that the chokes on the older trucks with a carb. were adjustable. If i remember right there were little raised marks on the choke housing for advancing or retarding the choke. All you had to do was loosen the screws for the cover and twist to adjust it. There was a spring inside that contracted or expanded according to the heat from the engine. Its been a long time since i've had a truck with a carb so i can't say this is your fix so maybe someone else will chime in with a more presice answer for you. Good luck.