Ia m helping a freind try to fix his issue, He has a 2001 Ford Expidition 4x4 with a 5.4l engine. When driving the truck Normally everything opperate fine, only when he depresss the accelerator quicky and to the floor will it just stop acclerating and lose all forward momentun. If he does it slowly everything is fine. When the truck is in park or nuetral and you depress the accelerator quickly it opperatesd like it should. It ONLY happens while in gear and does it at any speed 5mph-70mph, There are no codes active or stored.