I HAVE A 1996 BUICK PARK AVE ULTRA.IT SAT FOR TWO YEARS WITH 3/4 TANK OF FUEL IN IT.STARTED RAN ROUGH KEPT DIEING.TOOK OUT THE OLD FUEL AND PUT IN FRESH FUEL IN.STARTED GOOD RAN FOR ABOUT 40 MIN THEN DIED.COULD NOT GET IT STARTED TILL ENGINE COOLED DOWN.ONCE COOLED DOWN IT STARTED UP GOOD RAN TILL IT GOT TO NORMAL TEMP THEN DIED.

When the car is at a point where it won't run get some help and have someone spray a small amount of starting fluid into intake while you crank it over. If it runs for a few seconds then you know you have a fuel related problem. If it still doesn't fire look toward ignition related issues.

it has a new fuel pump in it and we checked to make sure it's geting fuel and it seem's to have good flow.

fuel filter changed too? if it ran for forty minutes, i'm thinkin temp sensor or MAF. best to check for trouble codes.

I would run the starting fluid test still and makes sure your getting enough flow AND fuel pressure. Next items to check are cap, rotor, ignition module control, ecm or pcm. Also there is this recall for your pcm. I found this on a Buick forum.... Item Affected: FUEL SYSTEM, GASOLINE:FUEL INJECTION SYSTEM Date Announced: 7/8/1996 Description of Recall: A BACKFIRE DURING ENGINE STARTING CAN CAUSE BREAKAGE OF THE UPPER INTAKE MANIFOLD. Action Needed To Fix It: DEALERS WILL UPDATE THE POWERTRAIN CONTROL MODULE PROGRAMMING. UNTIL THE CAMPAIGN REPAIR IS MADE, THE VEHICLE HOOD SHOULD BE SHUT WHENEVER STARTING THE VEHICLE TO REDUCE THE CHANCE OF PERSONAL INJURY.