hello, my name is XXXXX XXXXX X will help you ..
the first thing to do is check the plugs,dist cap,rotor as well as the spark plug wires .
if it is running bad then you need to check these things first ..jazzmaster ..
the truck I was telling about is my dads and he just told me that it runs good until you let off the gas and that's when it backfires and puffs smoke and stall when you are stopped or slowed way down, a guy trying to figure it out thinks its getting to much gas.
ok, I would check for a vacuum leak ,this would make it look like it was getting too much fuel and in a sense it e extra air coming into the motor and responding with a call to the system to add more fuel at higher rpms the vacuum is less and thus it may run good or is using the fuel better ..
so look for cracked vacuum hoses ,or a open vacuum leak ...jazzmaster ...