Ok heres the scoop. I have a 1986 Ford Ranger long bed with a 2.0 four cylinder, 1bbl carb, 5 speed. This is the lowest of the base models that you could get. When the outside air temperature is below approximately 40 degrees F, The truck will not idle without warming it up for about fifteen minutes. If you try to drive the truck without warming it up for fifteen minutes, it lacks power at highway speeds. (even worse than it does when its warm) When you try and accelerate it stumbles. It will do this for the entire trip (no matter how long or short) untill you shut it down, let it cool off, then start it again and let it warm up for at least fifteen minutes. If the outside air temp is over 40 degrees, it runs normally but still takes a few minutes to warm up enough to idle. My first though is the choke is not working at all, but I cant figger out the air temp/ running problem thing. Any thoughts?