2007 Chevy Suburban, 65K miles
Let me start by saying I took this into to the dealer and they found nothing!
When I accelerate, I get a “flutter” in the engine. The best description of this flutter is that the RPMs go down about 200 or 300. I think it feels like it is sluggish when it accelerates. It is most obvious during the 35 - 60 MPH range, but you also see it when cruising at 70 MPH.
I tried adding some fuel treatment and ran some 93 octane through it to see if it was the fuel injectors, with no change in the behavior. No error messages or engine light is on. Regular oil changes and services (60K service, every 3K miles for oil change). Driving behavior has changed since I bought a Prius 3 months ago. It used to be driven 40 miles / day (+ long trips) and now is driven about 40 miles / week (+ long trips).