Howdy Skara. Have you checked the usual customers such as:
1. Clutch fan
3. Leaves and crud between condensor and radiator.
Also, if the fins on the back of your condensor (air conditioner radiator) are squashed flat, then maybe it is impeding air flow too much when you are stationary.
Another thought may be to just take it out alltogether and dissconnect the airconditioning system. hehehe...less weight, less power being sucked, can only be good
The only thing would be if you had an auto, in which case you would have to install a tranny cooler.