Upshifting HARD
 

Greetings,

I have a 2005 STS, V8, and beginning yesterday when accelerating from ~30 MPH and the transmission up-shifts it's like being hit in the back with a baseball bat. Any idea what could be causing this? It's one heck of a kick. Could low fluid be the cause? As you know, this is a closed system so it's not something I can check.

Mileage on the vehicle is 197,000.

ANY input greatly appreciated!

Best,

Lyman