Failure To Launch

I have a 1985 Cadillac Fleetwood Brougham. I bought it from someone who had it sitting for a couple years and the fuel pump needed replaced, no problem. It ran fine for about 2 weeks after getting it fixed, then it started giving me problems. The transmission seemed to be having issues shifting gears at lower speeds, but acted fine once I got up to 55+. The mileage dropped from 16 mpg to 4 mpg. It started stalling out whenever my foot wasn’t on the gas, and then finally it quit running altogether.

I had a mechanically inclined family member take a look and he said it seemed to be starving for gas but other than that he had no idea, it tries to start but can’t turn over. In the past year I have had the fuel pump, fuel filter, air filter, and fuel injectors replaced but I’m not sure what else to look at. I’m hoping it isn’t the transmission, we all know how expensive those are. Any ideas?

Gas tank needs to be removed and cleaned.

in addition to cleaning the gas tank, all fuel lines may be ruined by old gas gumming them up and maybe all the new fuel related parts, if you ve run old fuel thru them.

Hopefully that’s all it takes, that should be pretty cheap compared to the other options I was looking at.