Acceleration Lag - Intermittent
 

I would say try another gas station, your 86 might not be liking the quality for fuel at that shell. Atleast it's a variable you can adjust. Other than that, I have no idea

Thanks
 

It seem to be getting better with this new tank of gas.

I gotta say that I was trying to avoid ethanol blended gas, but lately I have been using 94 and my car feels much more responsive.

You could throw it into manual mode when you slow down to see if it's still in 6th gear. That way you'll at least know why there is slow acceleration. I normally drive in manual mode anyhow unless on the highway. It's more fun! :)

Are you dropping below 4000rpm? Sometimes I punch the gas and get absolutely nothing only to realize that this car makes approx 8hp under 4000rpm.

Sounds like you're trying to accelerate in the torque dip. You can get a tune to flatten that out, but you may run into warranty issues down the road. Just drive it in manual mode and you can stay above it. Your mileage probably went down because the engine isn't breathing winter air anymore.