The hunting when at idle is quite usually the idle speed control valve sat on top of the throttle body, which is usually fixed by giving it a good clean with something like brake cleaner solution.
In regards to your missing when on boost have you checked your plugs are they ok (condition wise) are they gapped right could be getting blown out when coming on boost.
Or failing that get it booked in with a specialist to give it the once over (if you have'nt already).
Hope this is of some help....