Sounds to me like the condensor fan isn't working. The lack of air moving over it at a stop would explain why the air gets warm and then cools off again when you get moving. TSB 08-002-003 addresses this issue. No guarantee this is the problem, but certainly worth looking into.
The condenser fan fuse (#39) in the power distribution center may open leaving the(MIL).
condenser fan inoperative. This may be caused by a condenser fan with excessive current
draw or by water collecting in a trough in the fan shroud and freezing in cold weather,
which can prevent the fan from turning. This may illuminate the Malfunction Indicator Light