Intermittent problem starting

This is commonly caused by a failing crankshaft position sensor or camshaft position sensor. They often fail by becoming heat-sensitive. As long as you are driving, natural air flow keeps them cool. When a hot engine is stopped, engine heat migrates up to the sensors, causing one to fail. It will usually work again after cooling down for about an hour.

Start by having the diagnostic fault codes read and recorded. The people at many auto parts stores will do that for you for free. If there are no fault codes related to either sensor, you will need a scanner to see which signal is not showing up at the engine computer.

Did you have the diagnostic fault codes read and recorded?

The next step is to determine if you're missing spark or fuel. If spark is missing, Ford has had a lot of trouble with their ignition coils, but your engine uses three of them, and it isn't likely they are all failing at the same time. They are driven by the Powertrain Control Module, and they are fed 12 volts from the "PCM Power Relay". Try swapping that with a different one like it. When the crank / no-start occurs, check for 12 volts on the red wire at the ignition coil pack. That should be there when the ignition switch is in the "run" position. You do not have to be cranking the engine for it to be there.

The next step would be to connect a scanner so you can view live data. Look at the cam and crank sensors to see if their signals are showing up during cranking. If one is missing, check its wiring and connector terminals. Normally this is where you'd find a defective sensor. When both signals are missing, look for what they have in common, which is their feed and ground wires. This is where the problem is almost always caused by a wiring problem, or the Engine Computer isn't powering them up.

If you have spark when the crank / no-start occurs, you're missing fuel. This usually isn't intermittent, but look at the fresh air hose between the mass air flow sensor and the throttle body. There can't be any loose hose clamps, cracks, or other leaks in it. If any air sneaks in that doesn't go through the mass air flow senor, the computer won't know about it and won't calculate the right amount of fuel to go with it. The mass air flow sensor is another good suspect.