When I bought the car a couple years ago, it already had the sc installed. I had some misfire issues as well and I took it to a shop for them to change out all the plugs and clean all connections and injectors. After that, it ran pretty good but the old belt was not wearing properly and slipping. I didn't get the power I should have.
I am not sure if I have the "Uni-T box" or not. Describe it and I will check.
I also upgraded to the latest sc kit at the same time I upgraded my clutch/flywheel so combine all that and I noticed a huge difference in power. Just now have this stalling problem every now and then. The new SPEC clutch supports up to 700HP so it's a lot more difficult to drive. Very short release point and grabs extremely hard.
Oh yeah, I shredded 2 belts to get to the right pulley alignment that would handle all the load. Really helps to have a good guy as your main mechanic!
So being a sc novice, have you had the error codes from the time of the sc instalation or did they increase over time? I ask because with the sc installed, the plugs work twice as hard and in essence get dirty and go bad twice as fast. you could have someone check them like I did.
Hope any of this helps.
onefstm - sorry, not really sure about the boost level.