GMC Sierra Surging on acceleration

[cwhankins]

Help. My 1999 GMC Sierra, 5.3 Suges affter accelration and re application of the gas. In short, I can accelerate and then take my foot off the gas, hit the throttle again and it beginns surging. Tach moves 300-500 RPM. Solid application of the gas stops it. Any Ideas?

[Toronado_85]

This sounds like a vacuum leak somewhere in the system. My 1999 GMC had to have the throttle plate cleaned up (did ourself) and it helped.

http://www.gm-trucks.com/forums/index.php?showtopic=51692

[99 shortbox sierra]

Mine has the exact same problem, replaced the fuel pump, wires, plugs, air filter, o2 sensors, and all i can think of is catalytic convertors, or a vacuum leak as well, but i can't trace it down. Keep me posted as to what you find, i'm gettin mine checked this weekend and hopefully it gets fixed, sick of throwin money at it and gettin no results.

[Toronado_85]

Found the problem on my truck. Tested with a code reader and finally caught the mass air flow sensor dropping out of its normal range and going back. Flashed the service engine light. changed and mileage increased 2-3 MPG, pulls the trailer like never before. Senosor said it was out of its range.