I have a 99 f-150 4x4 with a 5.4. I've had this truck for about a month now. Sometimes starting it up it will run for a few seconds then the rpms drop and it either cuts out and the rpms drop and pick back up. Other times they drop and the truck will shut off. I'm not sure what to do. I know almost nothing about the 97-03 trucks. I'm jumping up from a 79. This problem is really aggrivating me because of the money I just spent buying this thing. I appreciate any help given to fix this problem.
If the engine light comes on, take it down to your local parts store(AutoZone, Advance, etc...) and they can hook up a scan tool to help diagnose your problem. If it's not throwing a code, it could be your Idle Air Control valve. About 2 months ago, my truck kept dying at idle engine speed with no engine light. I was powerbraking into work. I got some good advice about my IAC, swapped it out myself and now it purrs right along.