have a 94 f-150 v-8 302 fuel inject. When the truck is cold on start-up it idles fine for 2-3 min. then idles down to stall speed, if driving it will pop and studder, then take off like a rabbit (not the VW one) It sounds like a vacuum problem but which one?
Clean or replace the Idle Air Bypass Valve (also known as IAC), and check the throttle body to see if it needs cleaning to.