Hi,
Saw your thread and thought I'd throw my 2 cents. If you're a post bacc most likely you're taking courses to show that you have overcome earlier difficulties in your undergrad career, shore up your gpa etc. Therefore to show that you can handle the rigors of med school you need to take NO LESS than 2 courses per semester and make A's. Going back to school and taking one course a semester and making an A will not show to ADCOMs that you can handle biochem, anat, cell bio all taken at the same time.
Additionally I've been told that you should plan to take a bare minimum 20 post bacc credit hours, ideally 30. Reason being is that 20-30 credit of straight A's shows a good trend that is solid.
Do the above, retake MCAT if necessary and you'll be good to go.
rmp