Lynn, Your right, its boiling all the way to the condenser.
If the furnace is 2 years old, did the a/c work last summer.
If so, then what changed, coil might be just dirty enough to cause this. Since it was already low on air flow, it won't take much.
If its the first a/c season for this set up. Get the 3 ton blower out of your hip pocket and install it.
Some manufacturers use 1 size blower housings for 2 or 3 different drives, just the wheel, and motor are different, check to see if thats the case with this furnace, and you might be able to change just the wheel and motor.