g'day

last mistake of my head change to rectify, i managed to cross thread a few bolts when i was bolting the intake manifold back to the head, and now i've got vacuum leaks from hell as some of the bolts won't go home.

its still runs and drives fine, no noticable power loss etc etc, my worry is just burning out the valves because of the leaner air/fuel mixture. After i turn the engine off there is a sucking sound for about 3 seconds while the pressure equalises.

how quickly should i fix this and is there any easy solutions?

mmm
rip off manifold

clean the threads
get new bolts

either helicoil the threads or repair them with a thread repair s**t
i got this at home and used it and it worked very well?