hi there,this is strange because I`v had a similar problem with my car (same model engine and year as yours) it had been a reacuring niggle much like yours,some times it would struggle to fire not allways when warm just as and how the car decided really.I had noticed the car was slightly down on power and the exhaust was sounding different which isnt to easy to notice from the rumble they make.however the diagnosis was not a happy one im affraid the cat has bassically gone on mine and as its been collapsing its been blocking the gasses making it hard to start when the car was on the ramps you could hear the cat rattling as it was nudged/tapped a bit more evidence found in the rear box aswell,its now having 2 new cats and new rear section bassically the job lot £750 for the pair of cats and I decided to fit a stainless milltek for the rest of the system,bassically not much change from £1600 quid really.
this may not be whats wrong with yours but as I read your post it seemed a bit familiar,it can be checked just to cross it from the list of bits it could be good luck with it
cheers matt
