[1979 GMC Sierra]

PRattenbury - the ignition coil, that would be a good guess...however the truck was running good up until the new tank was put in. It would be surreal if a new/unrelated problem happend at the exact time of the gas tank switch. But i can't rule it out.

Gumby - i'll have to try that.

old Rusty C10 - yes, it's the 79 in my signature and picture. Good idea, checking the gas filter is what we'll do next. We lowered the tank yesterday twice (laying on the ground as we don't have access to a hoist, and using the jack to keep it from falling) and checked all the hoses...but we never checked the sending unit or gas filter cause we didn't remove the tank completely. But thats what needs to be done now.