'94 940 Turbo: Stutters Badly/Dies in Gear

[internetatelier]

My 1994 Volvo 940 Turbo began to have trouble starting a few weeks ago. On a recent night, it started and then began to stutter and stall. I was able to coax it very slowly over a miles distance towards a safe parking area, when, voila, suddenly the stuttering disappeared! I drove the car on the freeway across the bridge and soon after descending my offramp, the stuttering returned.

Now, after testing the Catalytic Converter and replacing the Fuel Filter and Fuel Pressure Regulator, the symptoms are:
Idles Fine in Park,
Stutters Badly in Gear. Actually it cycles between reving and dying at about 4secs per cycle.

Any Clues?

BTW: The Tank Fuel Pump is whirring away but I cannot hear the forward Pump. However, when I remove the main fuel pump fuse when idling, the car dies. I am pursuing this line next, although I'd gratefully receive any know-how to help redirect or refine my search.

[niloc]

Check:
Plug leads
Dizzy/rotor arm
Plugs

Clean:
Throttle body
Idle valve

To see if the main pump is running, use a long screwdriver as a stethoscope. (Main pump under the car near drivers seat (LHD)). Tank pump can be checked with the long screwdriver against the side of the tank. There could also be an issue with the tank pump connections.

Start with them...

[internetatelier]

Thank You for the heartening response. The problem turned out to be the main fuel pump. I had attempted to eliminate this possibility by removing the fuel pump fuse and checking for an effect on the running state (wouldn't start vs idles fine and stutters badly in gear). This was apparently a faulty piece of logic, although I don't know why. Subsequent to my initial posting, I removed the leads to main fuel pump and found that the car still idled fine and reved and stuttered in cycles when put in gear. The in-tank pump provided enough fuel pressure to idle the car and allow me to rev the engine for only a second or two before subsiding for an equivalent amount of time.