ok i have this problem. let me explain the whole story. first i installed 415cc injectors and a 4:1 disk in my fuel pressure regulator but waited on the afc for a few days. car would boost to 9 psi where its set except from 3 rd gear on because a few bolts broke of my exhaust manifold causeing a leak. the exhaust leak got fixed and we installed the s-afc at idle an lo throttle the car runs fine excellent but under boost at about 5psi the fuel cuts off and the turbo stops. the a/f gauge goes lean also.it kinda of feels like the ecu is tellign the injectors to stop pumping or something i also had the missing link installed and im not sure if that interferes with the s-afc so i uninstalled the missing link but the car keeps doing the same thing. no matter what the settings are on the s-afc under high throttle the car does the same thing about 4-5psi. i have no idea what coule be the problem unless all the carbon from the exhaust leak cause like the map sensor or something to go bad. please help any suggestions

put the missing link back on.

And if that doesn't fix it, get a new map sensor.