Welcome to the forum
Does the CEL(check engine light) work?
Does it come on when key is turned on, it should?
And it should go off after engine starts, even for 2 seconds
So it will stay running at high RPMs, correct?
But won't idle
IAC(idle air control) valve may be stuck closed.
Remove the IAC Valve, two bolts
Plug in its wires
Turn on the key
The valve should open all the way for starting.
If it doesn't move then unplug the wires and try to clean the valve
Google: clean Ford IAC Valve
Doesn't matter what model they all work the same
Cold Engine won't idle with IAC Valve closed all the way.
When key is off IAC valve will be closed all the way
When key is on IAC Valve will open all the way, allowing extra air for starting.
That is why you will often hear engine RPMs go up on starting, IAC Valve is open all the way.
After starting computer closes IAC valve a bit to set idle RPMs, higher for cold engine and lower for warm engine.
When you hold the throttle open, higher RPMs, you are getting enough air into the engine, even with IAC Valve closed