My 01 blazer LT 4wd 4DR when warmed up will surge it seems when under a load like accelerating. Also does it at a red light after warming up. At normal idle I can feel it and see it in the RPM's. It doesn't drop low but it is noticible. Any ideas? Just bought it last week. I'm hoping it might just need a tune up...

 

It could be from a sticking IAC valve (located in the throttle body) which can be checked and cleaned as necessary. Or it could be a leaking EGR valve which also can be removed and cleaned.

 

Thank you. I'm really digging this forum. Seems like everybody is quite helpful and I'm getting a lot of info on my new truck.