2000 F150 idle speed doesn't increase when cold
My 2000 F150 (5.4L) just recently developed a problem where it won't increase the idle speed when I first start it in the morning or after it's sat for many hours. It starts immediately, but then dies unless I hold my foot on the accelerator. I have to do that as I back out of the drive & maybe at the end of the block. But once warmed up some, it's fine - idles at ~ 600 rpm. If I shut the engine off & restart it immediately or say, w/in a couple hours, it's still fine.
Is this a common problem when one sensor, etc., goes bad, that it only affects the idle speed when the engine's cold? I don't have a code reader for this vehicle, but guess I could buy one, even though can't afford it right now.