Fuel

2001, tahoe, 5.7 with 92,831 miles. My wife had an accident about a year ago since then we have had a fuel problem. The damage to the tahoe was in the front but the brush guard took most of the impact. The hood and 2 side fenders were replaced, along with the brush guard. When driving the vehicle it will suddenly go down to around 30 to 40 mph and acts like it is not getting fuel then will stall out. We sent it to the shop where they replaced the fuel pump stating that was the problem. Well the pump they put in somehow messed up the foat so it would not read any longer. The pump was replaced again and we did not have any problems again until just recently. I have had other people look at the tahoe but they are stumped on what the problem could be. When I got home last night I took it out for a test drive, when It is in park and you rev the engine it works just fine. When I put it in drive- it was very hesitant at first then I pushed the accelerator to the floor and it took off as it should. Has anyone else has this problem or know what it could be?