This is an chevy s-10 blazer. that seems to make a big difference. the engine is a 4.3 . it has an automatic 4 wheel drive tranny. the engine will start and idle with no problem but start to cut out when picking up speed and maintaining highway speed. if you floor the engine it will run like a scalded cat with no problems. it seems to be only during normal driving that the problem shows up. the fuel pump anf filter have both been replaced along with the fuel tank. the has been air at the schrader valve instead of fuel, so we bled the lines. the problems still there. any help would be greatly appreciated. thanks