I have a 1995 Chevy Silverado and it does not want to get past 2500 rpms most of the time Iv replaced cap roster wires and plugs and Iv timed it with a timing light and it ran good for a little bit then went back to only going 25k I tryed retiming it but it was in the same spot I put it in what might be the problem
Change the fuel filter it could be clogged if not it could be a weak fuel pump from old age you can pressure test them
I had something similar on a 94 I owned. There is a filter on the intake of the fuel pump inside the fuel tank. Best bet is change the whole assembly as the fuel pump has been stressed by running dry. Mine went in 2007. Requires dropping the tank. A pressure test at the carburetor will tell you what's going on just like Scotti said.
https://www.amazon.com/Sending-88-95-Pickup-Truck-E3621S/dp/B01DB5E4F2
