help me tune a friends truck

[_paralyzed_]

sounds like a glow plug to me. If you have access to a glow plug heater try revving it with the heater on, if it works then it's the glow plug.

never touch the low speed until the high speed is set. They work together and it is important to have the high speed set correctly first. If the high speed isn't right you'll just cause more trouble fiddling with the low speed.

if it's not the glow plug I suspect an air leak somewhere, or bad fuel. Fuel that sits min the tank will often have the alcohol evaporated out of it and it won't run worth a damn.