engine trouble

[rickw06]

hey just wondering can anyone help me, well the cars running like a bag of crap, i tink shes only firing on one rotar, i thought there was an injector down so i changed that, but then i noticed the exhaust was blowing quite badly, so i stripped her back and realised the gasket between the turbo and mani is broken, the mani is slighty cracked and was also leaking where the downpipe meets the rest of the exhaust so ive new gaskets ordered and getting the mani welded tomorrow, so basically jusy wondering wud this cause the car to run like a bag of spanners?