my buddy has an '02 with edge drag box, HRVP, airdog 150. . .bout a month ago his truck stalled at idle occasionally but ran good when he was driving (that was with stock fuel system, stock vp) since then he bought HRVP and the lift pump. . .everything works properly but his truck still stalls at idle - -runs real strong, especially now after mods, but sometimes just stalls at idle like he turned the key off. never stalls while driving/under load. any ideas?