f150 help

ok so here is the deal, I have the truck all back together just been body dropped and the theft keeps coming on when i try to move the truck. I can start the truck up, if i hit the switches it will kill it some times and if i put it into drive and try to move foward or backward it kills it. Has anyone else ran across this? Where should i start looking. Or better yet anyone know how to over right the theft. Thanks to any help i  get. and once I get it going I'll pull it out and takes some pics. 4 door layin body.

have you tried resetting the computer since you've hoooked everything back up? just do the old positive cable off for a few mintues reset.  if not, it would def be an electrical problem. i would look at the PCM relay. but relays usually only go out in case of a ground or a short problem. so once again electrical, obviously 

i'd make sure all your grounds are hooked up properly. One shorted ground can cause all kinds of chaos in a computer controlled truck. Are the grounds from the frame to the cab under the truck connected? everything on the firewall? I took pictures of every ground and plug on the firewall before i bodydropped my f-150.

do you have a remote start or aftermarket alarm on it that might be going bad? i know with those if you disconnect the batt you have to reprogram them since ford has chips in their keys. (that is if its a later model truck)