tiptronic or drive by wire? vehicle accelerates
 

my 02 S has 50K miles on it. it just started acting weird. when i accelerate slowly the engine revs up about 500 rpms when i hit 30mph. it sustains this until i reach abut 40 mph.

it doesn't feel like the transmission is slipping because the car actually accelerates.

it almost feels like it is downshifting. however, the light on the dash doesn't show that it's changed gears.

could it be the drive by wire system telling the engine to rev up?...or the transmission?...or something else?

anybody experience this?

My Tip only acts up when I am seriously throwing it around hilly turns. How many miles since the transmission was last serviced? Maybe some fresh oil and a new filter couldn't hurt?