help with drivability problems
 

I was out testing and tuning my 91 6 port turbo this morning. Everything went well ( minus a small engine fire) but I noticed that if i drove the car easy and kept it out of boost, every time I approached atmospheric pressure on my gauge, the car kind of lagged and felt like it was going to die. if I kept it well into vac, there was no problem, and if I was in boost, everything was great. Is it just an ECU issue?

A bit more information would be helpful. A few hints of how things are set up, for example. :)

gah, I never seem to include enough detail. The car is a 91 coupe. I am running an IHI rhb-5 turbo from an mx6 into a 1st gen DSM intercooler. I have a 35mm Tial wastegate with a 5 psi spring. For fuel i have an OBX 8:1 FMU, and also a SAFC-II, I have a set of 550cc injectors, but due to the low low boost, I didn't feel the need to install them. The problem only seems to occour when i hold it at about 25% throttle. It just kind of bogs and stutters.