When I am driving and hit a bump or cross the track my car cuts off? What could that be? I have tried to change spark plugs and wires, cleaned battery cable, and checked for lose wires.

Also check, clean and tighten the negative battery connections on the frame and motor. Also check alternator connections.

Dandy, is onto something...especially the 1/0 cable to the motor block~ motor needs power too (er um Grounding)...ignition..grounding for sparkplugs...that's the thing~

so what exactly needs to be done. I have had this vehicle at two different shops and has paid over 300 dollars. They each double checked the wires, plugs, and cleaned the battery cable.

the battery...the bighuge cables off the top of the battery....the Black cable....follow the black cable until it comes to a point with a lug and a bolt....undo the bolt....wirebrush off all the corrosion from the lug...wirebrush the chassis/ground the lug came from...put the bolt back in and tighten 'er down~ ta sall~

I'm in agreement. Your car is losing its negative ground connection and the probable cause is the lug on the engine block or frame. Your garage has probably failed to clean this end and has only be looking at the battery terminal. As a last resort there could be a dead short in your battery but that would be a long shot. mike

Has anyone considered a faulty fuel cut off switch? Not sure where it's located, but it's worth a look.