As the weather is getting well below freezing up here in upstate NY, I've had this happen a few times -- the car will begin accelerating on its own. If I disengage the clutch, the RPMs go up insanely (if I had a tach, it would be redlining). Stomping on the gas pedal and releasing it quickly (jarring the throttle cable?) stops the revving.

The situation is always as follows:
1) It's very cold outside, below freezing.
2) The engine has had ample time to warm up - it happens after 5-10 minutes of highway driving, about 20 minutes into my daily commute.
3) I'm in the process of accelerating from a stop (toll both) or when passing another vehicle.

Suddenly the car will lunge forward with (what feels like) more power than a 1992 240 usually has ;-) Jarring the throttle cable stops it.

I don't have cruise control.

I'm guessing this is a throttle issue, but the behavior is strange enough to warrant a post... If it was a freezing/sticking issue, would the car accelerate, or just stay at the same speed?

Thanks for your help.