This is a 1999 1500 4X4 Suburban with 140K miles. Starting at about 135K miles, it started having an intermitant vibration in the accelerator pedal. It's a rapid vibration, similar to that of a cell phone vibrator. Nothing accept the pedal seems to vibrate or make any noise. The most vibration is while just enough pressure is being applied to the pedal to maintain about 40MPH. It hasn't been taken to any shops, but the shops around here are rednecks who wouldn't think it's worth caring about. Any suggestions?

 

The 99 Suburban uses a cable that is attached to the throttle body on the engine, so if you are feeling a vibration through the gas pedal then the engine is transmitting it.
The vibration may be the engine or it could be some other part of the drivetrain that is transmitting the vibration into the attached transmission and up.

Check the obvious first and make sure that all the tires are balanced properly, this is inexpensive and may prevent you from chasing your tail in the end.
I would also inspect the throttle body and throttle cable and make sure that everything looks correct.

You could also have a slight misfire, are your plugs and wires in good shape?

 

Yeah, the plugs are fine. I frequently do tune ups and such. But like I said, the vibration is strictly in the gas pedal. The vehicle rides perfectly smooth, even at 80MPH and higher. The throttle cable is a good thought. I don't see anything wrong with it but I may be missing something. Thing is, it's only that one pedal vibrating, and intermitantly. Only when maintaining that suddle 1200 RPM pressure to keep it going about 40 MPH. It is my Grandmother's vehicle but I'm the one who pretty much maintains it. I may just convince a mechanic to give an opinion without charging for it.

Thanks for the input,
Brian