I'm trying to help someone with an old 1991 Fifth Avenue (3.3L) that's
been sitting in their driveway unfixed for a year. Symptom is that it
idles OK, engine revs smoothly to high RPM's in park, accelerates to 55
mph on flat roads if you're real gentle but stalls instantly if you try
to push it at all. The engine doesn't quite die unless you keep pushing it
but it takes quite some time to recover. It can't maintain 55 on even the
slightest hill.

The fuel pump sounded awfully loud for a luxury car so I started by
replacing the fuel filter to make sure it isn't clogged. It made no
difference in the problem or the noise so I gave in and bought a
fuel-pressure gauge. Don't have my tach with me but just guessing at the
RPMS, I'm getting a fuel pressure of 30 PSI at around 1,000 RPM and 22 PSI
at around 2500 RPM. Sounds like the fuel pump to me but I'll wait for the
specs to be sure. (Just to save me a little looking, is the fuel pump on
this car in the tank or external?)

I'm also getting a TPS code which is the next suspect in line if the fuel
pump is OK. Can this code be caused by a bad fuel pump, or is it a pretty
solid indicator that I also need to pick up a TPS when I run into town for
parts?

The engine codes a

12 Battery recently disconnected

41 Alternator field control circuit open or shorted.

24 Throttle Position Sensor

35 Cooling fan relay circuit open or shorted.

The battery was DOA from sitting for a year and I had to jump-start the
car, which may explain the alternator code. I'm holding off on the
cooling-fan problem until the car is more drivable.