Altitude problems

I've looked and looked through this forum, tinkered with the 400s tables, and I still can't get any satisfaction out of this A320 of mine. Here's my problem;The aircraft simply shoots off the runways at takeoff, but rapidly becomes sluggish in the climb. By about 26000ft the climb rate is is 400fpm. All my weights, speeds, CoG and everything else is fine, the aircraft just performs unrealistically.My simple question; which table am I really supposed to use, and at what point does it affect the 20,000ft and above range?(p.s. the cruise_lift_scalar in the aircraft.cfg has also been tinkered with, but only has the affect of tuning the whole thing one way or another, as opposed to reducing low altitude lift and increasing high altitude lift)Thanks...- daniel