Surging when going into drive

[GARY BRUNGARD]

Hey people, I have this problem when I put my truck into drive it surges foward from 600 RPM at idle to about 1000+ RPM when going into drive and you feel the truck lurch foward. I really notice it when the A/C is on it is hard to slow the truck down. I have a 98 Silverado 5.7 Z71.

[Carwhiz]

Would need more diagnosis, but from your description sounds like trans. GM goodwrench rebuilts are very reasonably priced.

[silicon212]

Here's another, stronger possibility -IF- this particular engine uses the MAP instead of MAF on the injection -

Press and hold in the brake without shifting the transmission. If it does it then, suspect a bad brake booster and replace the booster. What would cause this is a vacuum leak - the MAP sensor detects a loss of vacuum while the oxygen sensors detect a leaned out mixture, and the PCM suspects the driver might be applying some throttle and delivers some extra fuel to the injectors to compensate for the leaned out mixture.

[GARY BRUNGARD]

Thanks for the reply, but when I put my foot on the brake before I shift there is no problem it is just when it goes into drive it ramps up. But you bring the point of it running lean would a 130 deg stat make it do this because it thinks its cold? The other day I on my way to work I was doing about 85 to 90 mph and after that when I drove home it was fine.