Weird idle Probablem

Hey i have a probablem my idle goes up from 2 grand to 800 to 0 it bounces arround all the time and sometimes it stalls. i really dont know the probablem. how can i check for vacume leaks. i would also like to know how much boost can i run on my can i have hsk bov cat back exsaust and a filter? thanks

My car did that...didn't have any boost leaks but i switched out my PCV valve and things worked alot better, just a thought ;)

i could havea bbost leak but the tps keeps coming up on the scanner