My ford f150 will not stay running unless I keep my foot on gas pedal
Ford f150 won't stay running
Clean the throttle body and the ISC ports and valve assembly, if problem still exists, you should check the codes, it could be a malfunctioning sensor or a wiring problem.
Keep in mind your vehicle is 26 years old. Continued maintenance is a necessity. Resist the urge to begin purchasing parts. The vehicle runs now, and I suspect it runs to your liking, absent the current problem. I would suspect the fuel pump is good. If the throttle body is clean, it could be an injector, plug(s), wire(s), etc. The net will supply you with info on troubleshooting those various items.
Check for vacuum leaks. Old vacuum hoses are probably brittle
I have a 2004 ford f150 and mine would stall when coming to a stop. Replaced the throttle body and it was fixed. And that was over 4 years ago.