2007 HHR LT. About once every 100 miles at low speed the transmission will let completely go like it's in neutral. Cured by downshifting and shifting back to D. Also, at highway speeds (OD) accelerates good unless you floor it which causes it to again completely let loose but every time. Get off the accelerator for a couple seconds and it's back to normal. Shifts and acts normal the rest of the time. A friend checked it on a Tech II - no codes stored. I thought possibly the TCM until we found no codes. Transmission fluid and filter were changed about 6 months ago. I just checked the fluid level - perfect. Any ideas?

 

Welcome!

Sounds like a bad internal valve to .me. Professional trans shop, sorry.