Anybody else have a problem with the engine surging between 30 to 40 mph.
Started about a week ago. It doesn't do it all the time.

 

I posted this a few weeks ago. I'm wondering if we're experiencing the same thing?

https://www.chevyhhr.net/forums/problems-service-repairs-42/transmission-issue-23142/

BTW, since the dealer dropped the pan, its not doing it any more. Just a little bounce sometimes when letting off on the gas around 40-45. My Trailblazer does the same thing, and always has, so I'm not too worried about it.

 

I think mine is doin the same as yours. It almost feels like it's shifting in and out of 4th to me. Just a really small change... And it only does it between 37 and 43 mph.