5.7 Vortec out of a 96 Suburban. When I accelerate off idle it just falls on its face. It recovers somewhat when you get in the higher rpms. It was doing this last ride in November, thought it was fuel. Put walbro 255 pump and new filter on (5 micron) but still does it. Yesterday in the woods it was bad at times and not so bad at other times. In a bad bind or uphill it would literally just put, put, put, barely move with the gas to the floor in low range, first gear. If I had to bump something it would hesitate until the RPM's got higher then would kick in. It does it in high range on the road also. Notice a slight backfire here and there on the road. Took it to Advanced and it shows no codes. Pulled the fuel filter and it looks brand new. Any ideas? Jimmy thinks fuel pressure, but I don't have a gauge and none of the stores rent them. Anybody in town have one I can use or know a good shop that can diagnose the problem? Plugs and wires are a about a year old, found some corrision in the distributor cap but cleaned that in the woods, no improvement. Any ideas or suggestions would be great, I don't really want to dump money into various parts/sensors without any clue what the problem is.
