working on a freinds truck and needing some info. going down the road power loss comes on on the display and wont hardly run. no throttle response. stop and kill it then start it and runs fine. sometimes it will do it alot then it might not do it for a while. this is on a 2003 2500 hd 2wd with 6.0. hadnt put a scan tool on it yet to see what the codes are yet. any idea what it could be or where to start looking ?