I have a 99 f150 and of late when i start my truck the RPMs drop really low then the truck will just shut off. In order to keep it running i must keep my foot lightly on the gas. Could anyone give me an idea of what might be happening. I put a cut out on it not to long ago, would that have anything to do with it?

Thanks.

 

sounds like your Idle Air Control (IAC) is needing cleaned/replaced. Theres lots of stuff about it here. Do a search.

 

IAC is probably the problem.