I have a 2003 6.0 and don't know if I am fighting electrical gremlins or if I am fighting fuel or air issues. I finally got back to trying to figure out what is wrong with the truck and wanted some opinions on where to start. Last I fooled with it, I cranked it, and just let it idle. It was about 20-30 minutes and it's almost like it choked itself down. It was idling fine, cycling fine and not overheating, and slowly the RPM's fell until it fell to a point that it killed itself. I was driving it prior to this attempt and I would slowly lose power, until the point it died as well. There was no pep in the throttle when I got into it. I am starting to think its either a air breathing problem, or somewhere between the fuel sending and top end. The truck does have dirty electrical leads going to the battery and I will be replacing those tomorrow to ensure good quality terminal connections. I have over 200K miles, it has been used as a truck should, and has over heated in past long haul trips, when this happened I would pull over and let it rest, Battery leads do have good connection, voltage is sufficient and stays above 12.4V. Can anyone possibly point me in a direction of where to go? ICP, TPS, fuel pump, idle air controls?