whether it is hot or cold, clutch pressed or in nutral every time it returns to idle it surges 3-400 rpm. any thoughts Thank you for any response
no upgrades and no dtc codes witch confuses me usually means mechanical, but it runs fine

Welcome to the site, some information please.
mileage?
does it have the GMTU upgrade?
how long has this been occurring?
if I leave on a train from Brooklyn, oh never mind that one!

no upgrades and no codes ,
couple of days
70,000

Any possibility there’s a loose clamp in the charge pipe?

So it returns to idle, and then a little surge?

yes if you start it it idles fine, after moving it surges. let the clutch out say in reverse then apply the brakes is when it happens

anything is possible i haven't checked anything yet looking at possibilities before i wreak havoc

Vacuum leak at the brake booster?

These statements seem to conflict. Please try to state the issue again.

It doesn't seem like you're having the issue described in this thread, https://www.chevyhhr.net/forums/ss-s...s-14468/page7/