[1979 GMC Sierra]

Thanks a lot guys for all the info and insights! I appreciate it. So far, indications are that it was what I suspected, water in the tank, making it a fuel problem as a lot of you suggested. I checked the gas filter and it was hard and you could barely blow through it. Had to clean it up (bought a couple new ones now, but wanted to see if the truck would run first), and I could then blow through it better.

Also, was able to siphon most of the gas out with a hose (was hard to get the hose into the tank, worked at it for awhile) and there was a bit of water at the bottom of each pale we used. So I had water in the tank, got bad gas somewhere then. Put the gas back in the tank after separating it from the water. But I don't know if I got all the water out of the tank cause you can't see how the siphon hose is sitting inside the tank. I started the truck and let it idle for a half hour, then I drove the truck for awhile and there was no issues. Dumped some more water eliminater/de-icer into the tank today.

I'm thinking of buying some 99% Isopropyl, like hatzie mentioned, and dumping it it to try and clear up any water I missed. Any idea how much I should or could dump in?