2002 gmc sierra 3500, 8.1-flashing mil, dies/hard to start

I have a 2002 gmc sierra, 3500 with 8.1, the truck will start immediatly(sometimes takes minute) and drive but after some time could be minutes to hours it will die. mostly if i'm at stop light or at low speeds less than 40. IF it dies I can pull over wait around 20 seconds and it usually starts a few times it has taken longer up to 30 minutes. The light used to not come on at all, then it started coming on/shutting off. Now it would flash then go out. from my research I heard flashing light is not a good sign. Thought about buying a diagnostic scanner since paying someone to do it will cost just as much, but like everyone else in this economy situation dont' have alot of money. So hoping to do some just brain storming before going the expense to get some ideas from those who maybe have an insight on my problem.

I reside in Olney, md

You must get the codes read for any meaningful help here.

I have an '02 8.1 as well and have had the same issue. I've had a bad crank sensor do this in another vehicle and have heard they were an issue in the '01 model GMCs. Mine stored code p0100. Can anyone point out where the crank sensor is on this engine and the cam sensor as well, provided it has one?

Check the info at autozone.com, repair guides, register and your in.

autozone has nothing for me, anyother suggestions?