only when the car is started. when you first put your foot on the pedal and start to apply pressure there is some resistance, then the pedal operates normally. but the initial push causes extra effort to engage the pedal so i jolt forward. I cant see any thing in the way of the pedal that might cause this, and the throttle body seems to be operating normally manually when i push on it (no excess resistance)
what might cause the initial extra pressure to engage the pedal?

 

check your throttle cable to see if it is getting hung up anywhere

 

Cleanthe throttle body, it's the throttle valve sticking to the throttle throat. While you're there clean the IAC as well.

 

If the car has cruise control, remove its cover and check the linkage inside.