Hi Keith,
Go here to see our articles on cleaning a/c and blower motor:
http://www.mobilehomerepair.com/hvac/articleshvac.html
Use bleach solution on coils and pan/drain line.
Pleated filters sometimes restrict airflow, I would use Hogs Hair filter material that is 1/2" thick and you cut to fit and place behind
louvered door panels.
You can get it at HVAC and Plumbing Supplies and sometimes at Wal-Mart.
Precision Air makes it for Wal-Mart and it is blue and woven cut to fit material.
Try that and see if it helps any.
It does sound like mold issues. Also, lay flashlight down in one register into the duct, go to next register and look back toward light with mirror.
Do this at all registers to inspect the ducting.
Thanks for inquiring,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?