Acceleration on its own

Yesterday in MN when it was -17 while on the highway around 5 pm my 96 Audi A6 started accelerating by itself. I was able to get of the highway and to a parking lot where it idalled in park at about 4000 rpm’s before I turned it off and let it sit for several minutes. I started it twice the second time it did not rev up to 4000, it was just normal. My question is this a sign of something terrible or just the cold messing with my old car? Should I have something specifically checked out? Thanks

It is possible that a gunked-up throttle body could cause the accelerator to stick, and this situation might be exacerbated by very cold weather. Have your mechanic take a look at the throttle body.

Assuming this car has a throttle cable it’s possible that some moisture froze and prevented the cable from moving, thereby locking the throttle in position. When you parked the car the heat from the engine melted the ice and the cable started working again.

Just a guess, but I’d say it was the temperature more than anything else.