Car gets stuck revving over stuck

2001 Buick century starts revving when gas
pedal is depressed past @halfway and/or
goes over @40 mph. It was intermittent for
months but does it every time now.
Mechanics, both certified and shadetree,
have looked but are baffled. I cleaned the
throttle body and it persists. The pedal isn't
affected so I can't put my foot under it to
stop it. It also can't be done from the throttle
from under the hood. I tried ruling out the
throttle. It only stops after turning the car off
and sometimes continues when I restart. I
have to turn it off in DRIVE so I won't ruin the
transmission. I just drive on the backroads
under 40mph. It's fried 2 sets of brake pads.
I am at a loss. Any ideas? Sound familiar to
anyone? THANKS!!