1999 GMC Suburban

I have a suburban 98 XLT 2500, and in general I love the powerful engine and the handling. I have two problems with the vehicle. One is the air conditioner which is not powerful enough (even compared to my old suburban 86). Also when you are in gear but stopped (like at a stop light) the engine keeps revving up. GMC is aware of this but there is no solution apparently. The transmission does not seem to disengage properly. I have taken the care several times to be repaired, and they checked the torque converter, then replaced the transmission but to no avail. Last thing I was told is that there was a software fix coming, that was 4 months ago.
I cannot findout how prevalent this problem is, but even if this does not affect the car's operation, it is certainly annoying and fot the top of the line 40,000 dls truck which I paid, I expected better.