car is stalling
 

hi i recently just tried to turbo my na 89 supra. halfway through i decided to stop because it was getting too pricey. i put back the stock exhaust manifold but now the car stalls out unless constant gas is applied. i used my stock oxygen sensor in the turbo because the turbo plug was differant...could this be my problem? if so how can i fix this? any help would be appriciated.

thanks