For a while, I've been experiencing my 2008 HHR will surge or lope at lower speeds - usually most noticable under 40 mph. I've also noticed when slowing down from highway speeds - like turning onto an off-ramp - there's a noticable down shift when speed drops below 60 mph. I've had the transmission flushed twice in its lifetime - would it help to actually remove the trans cover and replace the filter and fluid? Oh, yeah - it currently has 234k miles on it. Thanks, Rich

 

At that mileage it could be anything. My best thought would be to drive the car with a scan tool on it to look at sensor readings when its acting up.

 

Okay, the obvious question: Did you forget to mention the Check Engine Light is on?

If not; my guess is one of the valves in the trans is mucked up.

No, I don't think a new trans filter would help.

 

Thanks, guys! No, there's no Engine Warning light or any other fault codes. If there were, I would have already the scan tool connected to see what was going on. The engine is still running like a Swiss watch, so I'm more inclined to suspect something going on with the transmission. Thanks, Rich

 

There has just been a rash of "oh, the CEL is on" after 10-20 troubleshooting exchanges.

 

Clean the throttle body and MAF sensor, and as there are no codes double check for loose ground wires and have the battery load tested.
Inspect the TCM harness for any loose connections

 

i had similar problems, never a CEL, it was the shift solenoids inside the tranny, A code reader with trans codes can detect if it is that..