just today my car started to play up. its a r34 gt-t triptronic. 1st gear is good. 2nd till 4th runs very slugish and wont rev over 3000rpm. once hit 3000rpm it feels like the car is held back, drops revs by a touch and just holds under 3000rpm. any ideas what the problem could be. very few mods done to the car. voltage stablizer, 6000x300x105 fmic, blitz pod, hks front pipe, blitz cat-back exhaust. other than that nothing has been done to it. need the car for easter weekend. and apparently when car is held back after 3000rpm black smoke is poured out of the exhaust. help will be greatly appreciated guys. cheers