MKIII supra bucking

[supra red]

I have a 1988 toyota supra 7mgte turbo. it is bored 40 over, has hard piping for the IC, hks ssqv bov and a 3" down pipe leading to stock exhaust. other than that is stock. just got done rebuilding the engine. replaced the TPS, both knock sensors along with a new stock turbo (ct26). the engine idles at 650 RPM smoothly. a slow rev will go to about 4k RPM. when reved quickly you can hear the bov release but can hear chatter from the turbo and throw a code ( 52 = knock sensor). the car will drive fine as long as no boost but once boost builds it starts bucking and cutting out. have checked all the couplings for the IC piping and have a MAF on order. timing shows to be good. any suggestions