When I have my heater on high. It works fine. When I accelerate alot more air will come out of the defrost vents. When I let off the gas the air slows down. Is this my blower motor or is there some kind of vents that work off of a vacum under the dash?

You should have vacuum operators for the heater case. I would use a vacuum gage and check supply to the heater case. A lot of times a hose will get a leak and cause this problem. Vacuum operators also go bad. Just use your gage and follow the hose. Check engine vacuum also.