POWER PROBLEMS

If it's a manual transmission, the clutch is worn.

It is a manual trans I have a stage 2 clutch and it doesn't pop me out of gear when it does it.

A worn clutch won't pop you out of gear. It will slip, spin the engine and not move the car.

It could also be an engine issue and the computer is "holding" the motor back to protect it and prevent further issue, if it was a clutch I would expect it to do it in all gears, first should be a bit worse if it were a clutch cause your using it to first try to get going. Does it have the CEL lit up or flash the CEL at you when it's displaying the issue? Another question, as you stated you have a stage 2 clutch I would guess you have other mods done as well, can you list them; larger turbo, intake, exhaust, injectors, fuel pump, engine tuner/ecu programmer? Any of these upgraded. If you've raised airflow into the motor and exhaust flow out of the motor too much without increasing fuel you could be leaning out too much and then the ECU will definately hold you back.

When you step on it, do the RPM's climb faster than the car accelerates? If so, as tenspeed said, you have a slipping clutch.