Hello everybody this is my first post I have a problem that I think is easily solved and I'd like some advice. My 1999 GMC suburban revs from about 500 up to about 950 in a constant repeated revving at idle as well as at a stop while driving during the stop while driving at the height of the rev the vehicle will try to lurch forward I believe this issue is just merely the fact that the vehicle is revving at idle and I'm wondering what's causing it any thoughts?

 

remove the intake air snorkel and inspect the throttle plate. If it is dirty, clean it. move the plate and make sure the shaft has no play...if it does replace it.
if it uses an iac valve..unplug it and see what happens.

 

Thanks for your reply I was wondering if people still use this forum. So You're thinking air is making it past the throttle body? I'll go inspect those two things.

 

if it has a hunting idle...maybe the iac is stuck. Maybe there is a vacuum leak.

 

So specifically what it is doing is revving from 500 to 950 quickly and then straight back down to 500 and then right back up to 950 again it's a constant loop. When it's in drive at 950 at the height of the rev the torque converter will attempt to engage so it will buck at a stop with your foot on the brake and lurch you forward. I didn't get to the vehicle today but I appreciate your help and once I look at it probably tomorrow I'll get back to you. One of the first things I'm going to do is make sure that the snorkel is seated securely sealed on the throttle body because the gasket is bad and I put a bunch of rite stuff on it to fix that leak