First off I did a search for vacum leak and vacum line, and didnt find my problem. I have a original LS motor, I recently did a clutch job, I start her up and the RPM is high like 2300 rpm, when she settles after getting warm she falls down to like 700 (normal) and jumps back up to 1500, then falls and jumps between 1300 and 1500. To me it all points a vacuum leak. But I want help on where I should look first to diagnose my problem. Or how do I diagnose my problem. Could it be the EGR valve gone bad??
kinda sounds like a fast idle thermo valve issue. I have heard of problems caused by the FITV that sound like what your having. Try bleeding all the air out of your cooling system. It’s just an Idea…hth
Just for an update. I pulled off the FITV and turned it back in, it helped a little but I still had problem. It turns out there was a hose loose that goes into the back of my intake manifold. Thanks for the help all.