1993 Lincoln Town Car Intake/Fuel System

Engine Performance problem
1993 Lincoln Town Car V8 Two Wheel Drive Automatic

I have a 1993 Lincoln that ran perfectly fine until about a month ago.
It started to sputter and die every couple of miles, mostly at red lights when it was idle, or when I'd attempt to accelerate (at any speed) uphill, or if I accelerated too quickly (more than 3-4 mph) from a stoplight/red light/parking spot.
I cleaned out the fuel line, replaced the fuel filter, and was told that it was the intake plenum that was causing the problem, as it has a couple of cracks in it. Is that what would cause this, or is the fuel pump? Apart from the pump, I have replaced or cleaned nearly every other part to this system.