Check engine light on

What year F150? Newer? Is it cold right now where you are? It is normal for most fuel injected, computer controlled engines to run at higher idle speeds in colder weather (kind of equivalent to a choke) It helps warm up the engine faster. As long as the idle speed gets close to normal when the engine is warm and no lights are on, I wouldn't worry about it!

Check cable which plugs into back of instrument cluster. Also fusible links.

Sounds like a bad Throttle position Sensor. When was the last time fuel filter changed. Start with cheapest parts first.

The popping at idle and deceleration (when the throttle is in the idle position) could be a lean mixture at idle.
A lean mixture sitting at idle for a long light would cause the engine to run hot.
Also, as the engine reaches operating temperatures, the idle will pick up.

-Check for misefire.

mai

Low oil pressure at idle can be caused by an engine with worn rod or main bearings due to (usually) high mileage . This however does not mean the engine is still not serviceable as long as the oil pressure is low only at idle. The pressure should at minimum get into the normal range at anything above idle speed.Not much oil pressure is really necessary at LOW speed. At low speed, as long as there is oil getting to the bearings, even at low pressure, you are OK. In a high mileage engine the oil pressure is often low at idle simply because the oil pump is turning slowly and cannot maintain higher pressure between the larger than normal crankshaft and bearing clearances. As speed increases the pump turns faster and supplies more oil and the pressure should go higher. Low pressure as long as it is only at idle is not a problem. However at higher speeds the pressure should be in the normal range. Such a worn engine can benefit from higher viscosity (thicker) oil such as 20W-50 in above freezing weather and 10W-40 in winter. That will increase idle pressure and the thicker oil film maintains a better film between the worn parts

The distributor cap and rotor if it is not in the right place or order would change the timing of your vehicle causing this problem so you first should check the timing with a timing gun and know how to use one but if you do not then try to have someone else that does and check timing first.

Hi,
You need to get your engine coolant thermistor checked and tested. This is what tells the ECM when the engine temperature is at normal working temperature and turns the idle down.
But when the idle won't come down from cold to warm this is usually the main fault.
Hope this helps.
Thanks
Jason

has anyone put the lab scope on ignition yet

take your car for a tune up
if they are carburetor type motors you may need your carbie cleaned and a tune up
if you clean it your self with carbie cleaner it may increase in idle speed this is nothing to worries about it is a simple adjustment
with a carburetor type motor they tend to idle higher when their cold this is the automatic choke kicking in and normally it should happen till the car is a bit warmer and the accelerator has been depresses
although a car should idle at 800 rpm my paddok car dose when it is cold it idles at 1200rpm i like it this way as the car warms up quicker as i will not drive a car while it is cold
hope this helps
ricko