Sometimes it will not start! It has a new

If it has sit for a long while, I might put a couple drops of oil in each cylinder, turn the crank by hand. You could jump the starter relay to get the starter motor to crank a little. If you try something like that, make sure tranny is in park or neutral and functional parking brake is set.
Your security system has the pellet in the key? You could try a relearn procedure?
Turn the ignition switch to start, then release to the on position
The security lamp should be on
After 10 minutes the lamp will turn off
Repeat the 10 minute sequence 2 more times, with 5 seconds between them
Turn ignition switch off. Hopefully on the next start attempt it will start?
Sometimes after a vehicle sits for a long time, little gremlins get to chewing on the wires, cause all kinds of problems. Any applicable trouble codes?

It sounds like...very frustrating. Really, a year?
If I understand correctly, sometimes the starter motor doesn't work? But every time the starter spins the engine, the car starts easily? If this is the case, then the problem is confined to the start circuit, which narrows it down a lot. Basically the starting circuit is the battery, the starter, and the ignition switch-and the wiring connecting and associated with the circuit.
It seems to be happening a lot now, so a tech with patience and understanding of your Focus starting circuit, should be able to have it occur and find the problem. It could be as simple as rust or corrosion on one of the electrical connections. The place to start is with the battery terminals and connections, the starter motor connections, battery ground connection and a couple of other grounds in the start circuit. The starter motor and attached starter solenoid could be taken off and tested on a machine to see if it has anything wrong. Parts stores will test them for free if people bring them in.
One thing you could try: you said slamming the hood might jolt something, and cause starting: sometimes you can cause a failing starter motor to turn on by tapping on the case. Find the starter- the positive battery cable is connected to it- and when it won't try to start, rap on the starter with a heavy screwdriver, or tap it sorta lightly with a hammer, then try to start. If it starts up, you have a failing starter. If it doesn't help, you will probably need someone with a multi-meter to check out the circuit.

i see dash lights on when you try start engine.could have faulty starter relay or bad starter solenoid or starter bad.use a 12 volts test light see if power going to starter.if starter circuit okay could have theft security problems because BMWS did have theft security key ignition system back in 1994.

does the starter actually turn the engine everytime or nothing at all sometimres?if it fails to tirn ovewr sometimes, it could be the bendix in the starter, or the solonoid switch ,sometimes its in starter sometimes its under hood

when you turn the start swich all dash ligth turn on ,if not battery has been consume.or battery cable still loose.

Sometimes the security system can shut off your starter. Other times, a new starter does not match up with the correct frequency of the security system and can cause a starter failure. Read up on this site. Check to see if the security light is on. http://vatspasslockpasskeysecurityhelp.yolasite.com/

How about the starter? My 1997 Cadillac Deville has this annoying problem where I can only get it started sometimes by toggling the starter switch on and off rapidly for 3 to 5 times before it turns over. lol.

Other times, it starts fine.

The only solution, assuming your security system isn't playing games with you, is to replace the starter with a new one.

Good luck on this repair.
:)

even if your starter is out it would still click when you tried starting the car. so try replacing your battery first thats the most common problem for random starting. also look under the car you may need to jack it up. look under the intake manifold that is where the starter is check to see that everything is hooked correctly and that all the bolts are tightend securley and not loose on one side.

To check the solenoid internal contact, you'd need to remove the starter and remove the solenoid cover. Inside you will find a brass wheel that contacts the positive battery lug. You can remove the wheel and reverse it and turn the lug 180 degrees, providing new contact surfaces. Seems that you've done just about everything else. You can also use a test light attaching it at different points to find where the actual delay is occurring. Normally security will allow cranking but will not allow starting.

when it wont crank, you will need a test lite to ck the small wire at starter for a 12 volt signal when commanded to start by the key. also make sure there is 12 volts from battery going to larger wire on starter. if so and still wont crank, starter replacement is probable. (assuming grounds are clean) they can be very intermittent. another quick test would be while trying to start, holding key in start position, rap lightly on starter with hammer to see if it kicks, if so, replace starter.