Focus Mk2 2.0L Idle Problem

Hello everyone, this is my first post, so go easy, but I don't mind constructive criticism!

I've had my 2008 Focus Ghia Mk2 2.0l for just over a year. For a few months I've increasingly noticed 2 issues which may or may not be related -

Starting with the engine cold takes about 5 or 6 cranks of the starter motor before ignition, when hot it is instantaneous. Four times (twice in cold weather, once in normal, and once in Spain where it was bl***y hot and had been running for several hundred miles!) it has failed to start - got it going after persistance mainly, but a bump start was needed on one occasion.

The most concerning issue is what I'm considering an 'idle problem'. When releasing the clutch to engage 1st gear revs drop dramatically from idle ~800RPM down to about 500RPM and will stall if I don't push the accelerator to keep the revs up. A few times it has actually stalled, through no fault of mine.

I've cleaned the spark plugs, the threads were a bit oily, but nothing ridiculous. And changed the air filter (which was the wrong size and didn't fit properly). Last night as part of my (failed) attempt to find the idle air control valve I took the throttle body off to see if it needed cleaning:

Inlet manifold: https://www.dropbox.com/s/uorxk9k6brfl3b2/2014-03-19%2017.55.15.jpg

Throttle body filter side: https://www.dropbox.com/s/0t9unkxw1dugldn/2014-03-19%2017.52.49.jpg

Throttle body engine side: https://www.dropbox.com/s/rzc72gl8z7if2zf/2014-03-19%2017.52.45.jpg

Cleaned the throttle with IPA, and apart from starting a little bit lively this morning, no change to the idle problem.

Hopefully someone can help or give me some advice on what to do next. Let me know if you need any more info... talking of which, the car has done 57k miles.

Many thanks :)