check the idle control valve and its plug, check the vac pipes, also check the throttle position sensor.
to be honest though, sound like it needs a set up, when was the plugs and leads last changed? fuel filler isnt due till 60000miles but could prob do with a new one if it never been changed.
whats the breathers like? free flowing or resrtictive?

my RS done it a bit, once it was set up it was sweet as a nut.
i had to have my fuel pressure upped andmy Co2 adjusted as i fitted a chip etc but you may just need the Co2 tweeked

PM me some more details of what you have checked etc.