Miss Under Boost - Help!

[Zorro]

Ok so i was giving it abit and now it has a big miss under boost! Any ideas what it could be? It is still making the same boost as before the problem (11psi), but its a pretty consistant miss & is losing alot of power & wont pull past 5 now!

Coil pack, plug, gasket, injector, pump...........???????????

[kjb_r33]

boost leak, check all your hoses and clamps

[Zorro]

ok well a big crack in the exhaust mani has opened up, could that cause a severe miss under load? (or is it coincidental?)

I can rev the engine in P or N and it wont miss, i can slowly bring the engine up to high rpm without it missing, but as soon as i load it up, open up the throttle or get any boost above 5psi its starts to miss, stutter & carry on!