jeff - there is a great product you can buy that is sprayed up into the evap case through the drain outlet --- this foams and cleans/disinfects and can improve air flow.

Also you may have one of two other problems...
1. air vent distribution issue from vacuum leak or bad vent actuating diaphram and/or...
2. you may be icing at evap which will also restrict/reduce air flow and cooling effectiveness. (cycle switch issue or improper freon charge #'s}

Did you get all that?

Greg