If you are still using the rubber piping SMIC, that could possibly be the problem. Before I installed my FMIC my car would feel great up until 3500rpm then fall straight on it's face. It would act terrible, going from 3, 5, 4, 2, 3 psi and never hold. I changed my WGA, checked for any leaks, but we could never figure it out.
Finally installed hard pipes (FMIC) and it pulls great. Right at 3500rpms you can feel the car pick up and once it hits 4500, she's holding nicely through out all gears. I'm not guaranteeing anything, but it solved my problem. If you don't want to invest in a FMIC, then you could go with standard hard pipes, anything that gets rid of those cheap ass rubber once.
