How to change fuel filter 1990 Cadillac deville

how about coils and module.

I believe you have a bad sending unit in the tank.

On the frame directly below the rear passenger door drivers side, above the E-brake cable and fuel return line. Be sure to loosen the fuel cap before loosening the outlet/inlet lines to the filter or fuel will continue to flow due to pressure in the tank also have a container to catch what fuel is in the filter/line. A 5/8 and 13/16 wrench should be the tools to use.

If the fuel pump is original to the car & I would
doubt it,then that is the problem

Does the fuel pressure drop before it shuts off

I like to road test with the gauge taped to windshield
or tied to a wiper arm

You have to determine what your losing at the time it shuts off

I think you should have 55 to 60 # pressure

You could put that question into google for the answer

Get the throttle position sensor checked and the 0/2 sensor. Check vac. hose to map sensor.

I had a 1990 cadillac deville with a bad computer that wouldn't deliver fuel to one of the cylinder's injector and this caused it to buck at 35 mph.

check pressure relief valve

Had a computer on my 1990 Cadillac Deville bad, after changing plugs, wires, cap, fuel injectors, egr valve, etc.

The computer was not firing an injector and i had a miss and rough running mostly at 35 mph on the roads. It bucked like a bull.in a rodeo.

wow...BIG problem...I'd say you have a bad ECM - maybe you hooked it up "hot"? otherwise, check all grounds for secure connections.
Good Luck

I would first replace the FUEL FILTER. If problem persists, make sure exhaust is not partially clogged like a clogged catalytic converter. Hope this helps