Oldsmobile/Buick Repair: wont stay running after about 1 hour, check fuel, poppit

Question
we have changed the cpi and fuel pump and the  and the ecm it will start but after an hour of running if you step on the gas it it brakes up and misses and then dies and will not start...
      Please help !!!!!! Its an 1994 Bravada olds mobile 4 wheel drive 4.3 engine  

Answer
hi deborah.check fuel pressure when it won,t start this vehicle has to have a min of 60 psi to open the poppit valves.even if you changed pump if you do not have 60 psi when it won,t start you got a bad pump very common with this truck.if you have fuel pressure when it won,t start then check if plugs are fireing if not ignition module is bad.please rate my help sorry so late puter probs ty billymac