[unicoladron]

you bolted a t28 turbo to an engine that is tuned for a t25. this turbo has the ability to force MOAR air into the engine. now with this larger turbo you've bolted on that can force more air, have you done anything to your fuel system to match the larger volume of air coming into the intake?

this won't fix your problem, but you should definitely have a higher volume fuel pump.

you either need to get an AFC (air/fuel controller) to tune with to tune your a/f ratios, this will allow your engine to run a little more stable.

maybe a cheaper route would be an adjustable FPR, but i'm no tuning expert.

your engine probably idles fine, but once it hits boost, it dies because you're way too lean, because too much air is coming in and not enough fuel.

also do you have a boost gague? if so, do you have a boost controller? what are you currently boosting?