I was driving around 65mph in my 85 190E 2.3 - when I came to the exit, I realized the throttle was stuck. I braked hard but that slowed the car only gradually. Thankfully I pulled into a vacant lot, and killed the ignition to stop the car.

This has never happened before. And it seems to be back to normal now, but I am concerned about driving it again until I show it to a tech.

What could be the possible culprits?

Thanks.