Electrical ghost in 96 buick lesabre

You need to get yourself a schematic and find out where these systems have common connections, where the ground are, etc.

I have a service manual that may be good enough to help. I'll take a look and see if I can point you toward some things to check

On this car, the windows are operated from a 'hot on run' bus. If they don't work, it is likely because they are all burned out (unlikely), because there is something killing the voltage from the bus, like a bad connection, blown fuse or circuit breaker, etc, or because there is a bad ground somewhere.

The fuel pump operates under control of a relay which is activated by the PCM (Powertrain Control Module) on the signal side. The power to feed the relay comes from the 'hot on run' bus, so if your 'hot on run' power is missing or decreased, the fuel pump won't run properly even if the relay activates. There are some points of common ground from the PCM also.

If you want to fix this yourself, get the schematic.

The fuel pump replacement you recently shelled out for may not have been necessary, but that is hard to second-guess. I would say you have electrical problems further back in the system