Thats a tough one. I have the exact same car and have never seen anything like that.

A few suggestions, and I'm just taking shots in the dark...
- Try a different ECU. My 91 came with a PM9 ECU but runs much better on a PM5 ECU from an 88 Standard. I don't know why, it just does.

- Check the injectors. One might be sticking open and just dumping fuel.

- Check the fuel pressure regulator. It might be stuck.
I suggest installing an adjustable regulator with a gauge. The Si regulator will fit if you flip it upside down and do a little grinding on it.
I actually run a pretty high pressure in my car. About 45psi. People always say "Thats too high" but the car runs great. The dual point injection is kind of an unexplored area, so who really knows whats too high and too low?

Thats about all I can think of right now.
Good luck with it, and bring it down south some time. The ARRC is the most fun you'll ever have at the track