This truck has rusted horribly.
It gets no more than 9 miles to the gallon.
I replaced both the starter and the alternator.
I was very disappointed with this truck. I expected a 1/4 ton with a V6 to get much better mileage.
The rust on this truck has to be seen to be believed, It must have had some kind of defect from the factory as it rusted in places that are normally protected, like the top of the roof and the middle of the hood. However this truck always started well even at 35 below, which we see quite a lot of here.
I have owned 2 GMC trucks and I have never had the problems that you have had. But I must ask you, if you have kept up with the maintenance. Like changing the air filter and the oil changed every 3000 miles without fail? Or the spark plugs or spark plug wires. Also the after market has a lot products that can help you with the gas mileage.
I agree with the other guys comment. The rust is your problem. You can't just buy a truck and expect it to maintain itself. My '89 S-10 has 179000 miles on it and I have only had problems with the starter. I maintain my truck myself and that's why it has proven true to me.
I seem to have problems with my 1989 Chevy s10 pickup. now I have water in my oil and my engine is full of antifreeze and I can't quit figure out how to go about fixing it. that is the only problem I've had with my truck.