my bud's 99 GTP will occasionally accelerate through first gear at full throttle without him pushing the gas. its pretty scary cuz he would be sitting at a stoplight and when it turns green he would let off the brake. the car would start to roll forward but then take off like a bat from hell. i know its not him just messing around because ive driven his car and experienced this problem. it is a pretty big safety hazard considering we live in a highly populated area. it's also killer on his brakes and transmission considering he has to stand on his brakes with the throttle wide open trying to prevent his car from ass-ramming the car infront of him.
ive looked inder the hood and everything checks out.
does anyone have any idea what this could be. his car has ~120,000 miles on it, which isnt that many for the 3800 series II. any input would be great

What are the rpms at idle in park or otherwise? Obviously the idle is set too high for some reason. Could be a broke IAC, messed up throttle cable, or something is blocking the pedal from returning 100%. Odd to say the least.

Isn't there a spring on the peddle to help bring it back? Chech that first.

Then I think checking the cruise control would be a good idea.

I don't think it's too high of an idle because it's only occasionally right? AND the car acts as if the pedal is to the floor?

Only the driver and the cruise control have control over the throttle so I dunno.

the pedal is all the way back. i will check the cruise control. maybe its telling the car to accelerate.

I thought cruise control automatically disengaged under 30mpg on most cars. I could be wrong.

Most of them must not work then.

Actually, try disengaging the vacuum line to the cruise and see if it still happens.

pull the cruise cont fuse. maybe a sticky throttle? try shootin carb cleaner around it, doesn't hurt to try.

Maybe a bug in the computer.
Try disconnecting the battery to reset the PCM. Leave it disconnected for about 20 minutes.

My mom had that same problem and her rpms was always above 1100 and it was her idle motor which are common to fail in fords from what I was told.

I had that happen to me in my GP and it happened to me when I had my monte carlo. Not sure what was the cause, but everytime it happened my cruise control was on, but not engauged.