[Downeaster1]

This issue has me almost completely baffled.
Whenever I'm driving around 70-80 on the highway, occasionally it will feel like the throttle backs itself off to about 5% power without any movement from the accelerator pedal. It happens sporadically, but when it does, it's always when going around a corner or a slight decent (still on the highway mind you). I first noticed it when in cruise control.

Some notes: This reduced power/slight lateral slipping feels like it's coming from the back area. The rear tires are the factory runflats and have about 5/32 left on em. Other than interior accessories, the car is factory.

Any ideas?