Does this sound like a fuel pump problem or ignition failure?

[chan@seattleu.edu (Anthony K.B. Chan)]

Hi guys,

Does anyone know if there is a screen inside the fuel tank of an 85' 5000s?

My 5000s just started with this weird problem last weekend, it will suddenly 
lost power and then stall completely but you can start it right up. It usually
happen after at least one to two hours of driving. The fuel pump was replaced
about 16 months ago. It usually died after a buzzing noise from the pump.
I replaced the fuel pump relay. I have the fuel pressure checked also volume
checked. My mechanic even hooked up a fuel pressure guage to the fuel system
and drove around with it for 4 days but of course nothing happen, the 
problem never reappeared. The pump was real quiet. He checked a bunch of other
stuff like the fuel accumulator, differential pressure regulator(just been
replaced a 2 months ago), fuel filter been replace. Also all five fuel 
injectors were replaced 8 months ago.   

It cut out 5 times on the freeway last weekend, it was fun diving for 
shoulders! :P 

Does anyone have any idea what causing the problem? 

Anthony Chan
Adminstrative System
Information Services
Seattle University

chan@seattleu.edu