Accelerator shaking on 96 F150 I-6

When accelerating or decelerating, my accelerator pedal vibrates and makes a little noise. I don't think it is a rouch accel. cable; it was lubed a few days ago and it didn't fix the problem. The vehicle itself doesn't shake, just the accelerator.

Aha! I found the problem. On the engine, there is a brace between the throttle body and the block. One of the bolts was missing; replaced it and it does fine now.