I have a 1988 Toyota pickup 2wd that runs rough and wants to stall when I first start it . After the temp gauge comes up a bit it idles down and runs perfect. It also blows black smoke and occasionally backfires when cold. I had a mechanic check it and he changed the choke pull off but it did not help. He said I need a carburetor . Anyone have any other thoughts or should I just buy a carburetor and have him install it ? He won't get the carburetor because he said too many of them do not work and he does not want to have to go through 2 or 3 to get one that works . Not sure if he is screwing me around . Thanks.