My forester always runs good. When it's cold starts fine, when warm it spins longer to start and finally catches. Sometimes it takes a while. I changed the starter and that was not it

Do headlights work? Do they get dim when you hit the start position, if so battery has bad cell.
Bad batteries might be OK after charging and running the car for a time but will discharge after car sits for maybe longer than a half hour. Usually a bad cell.
Take to auto parts store, they will load test it for free.

Maybe the ignition switch has a glitch in that power for spark is only relayed while you release it. I would try another switch on a hunch.

may need a good tune up. Fuel conditioner, or gasline antifreeze sometimes helps. You didnt say what type of car this is tho

Timing belt being off one tooth will not cause this problem but rather loss of power and hard starting all the time,

in the cold it will not start, the engine will spin but wont fire is this correct?

There are many things that can cause this, a little testing will be needed, the first thing that comes to mind with the ford and cold weather is the coolant temp sensor, it give computer a false reading and can cause hard starting or even no start, a scan tool would be helpful to see what temp it is give computer.
The best way to narrow this down to to check for spark when it wont start, a weak coil in cold weather will cause this problem or bad coil wire to cap, but if you can see if it has spark and let me know,
another test is to check fuel pressure, to see if it is getting fuel, and the fuelpump relay,

Let me know if it has spark or fuel when is does not start, good day

Normally problems starting could be the glow plugs these warm the diesel up making ignition easier also check the wires going to glow plugs if only 1 of these are off it makes starting harder

iwould check the selector motor,and also replace the thermostant,start with the stant first,the selector motor is what runs the door for hot or cold the motor is a common problem,if the temp gauge is showing a quick warm up temp then its the selector motor, if it takes a while to reach operating temp then replace the t-stant,also make sure the coolant is full in radiator,check when cold or warm,dont open when hot, hope this is helpful.

Your cold start valve is not opening to assist the firing. It function is to provide extra fuel to ignite the all combustion chambers easily. When the engine doesn't have this extra fuel from the cold start valve, it will take a few times to get it going. The cold start valve is turned on at the time of starting only if the ECM get the signal from coolant temperature sensor saying it is at a preset level. When the sensor is bad, it can give a wrong value so ECM think that temperature is hot so not turning the Cold start valve. Replace this coolant sensor first, then the next thing is to check out the cold start valve.

the fuel pump has a fuel pressure check valve in it, if this fails/sticks open the pump still pumps ok but the fuel drains back into the fuel tank in a very short time and creates the hard start issue you have described.

sound like the lift pump!

perhaps you need a new cap and roter a new spark plug wire set. they don;t like moisture. also check to see if you have any broken or leaking vacuum hoses. the worse case senerio would be that your head gasket is leaking--at cold temps a little antifreeze will enter until everything warms up and it seals shut due to metal expanding. but since you say it's cold weather only--this probably wou;dn't be the case. good luck.