I had a similar engine start problem with my s1 33. After being parked outside for an amount of time in the sun on a stinking hot day, it would take quite a while for the engine to start (which was f'ing annoying!) But once it kicked over, i didnt have any idle issues. I reckon Lance is correct about the igniter module in my case (as it was a series 1), although i am 99.9% sure the s2 33's dont have one.
I'd definitely look into blind_elk's suggestion, and do a bit of research about cleaning up the AAC valve - check the DIY section of the forum.