low idle problem

First thing I would check for is a vaccum leak. Raise the hood, with the engine running listen for a hissing noise. Do a visual check of all the rubber, plastic hoses looking for loose ends hanging off holes or cracks near the plug in ports. Repair as needed and see if that helps you out. Fords are known for vaccum leaks and will run slow or stall at idle. Vaccum is increased with the engine rpms and will run smoother then.

Agree with "torque wrench" and may also want to clean throttle bore of injection throttle body to help smooth out the idle and can also help with accel from stops.

One other item to keep an eye on for this truck is the MAP sensor (Manifold Absolute Pressure). This can affect fuel control and cause idling issues.