Sounds like your talking about the balance shaft sprocket(i could be wrong tho). Did your balance belt snap off or just the timing belt chew up? If just the timing belt i would check all of you pulleys and make sure there spinning freely.
Have you tried a boost leak testAlso you said you replaced you belts? Check to make sure their tight I've seen cars act wacky if the alt belt isn't tight enough.
Looks like your bov is not recerculated but you still have the bov hose comming off the intake snorkle is it plugged?Also you should look for a black top cas since its a hall effect sensor it might help you out
well if its a header back then its cutting out the catalyst converter which will more than likey throw a p0420 code(catalyst efficency) most people add a spacer to the bung in between the 2nd 02 sensor and pipe to help prevent the code from popping up.