power stoke shuts off

i just bought a 04 f-350 with the 6.0. before i bought it a company took a plow wiring harness out. now everytime i hit a bump the hole truck shuts off but will turn back on. does any one have any ideas.

Check your wiring coming off of the battery, there is usually a big wire going to the starter and a smaller wire that powers the rest of the truck, there is probably a loose connection somewhere along the small wire.