Shut the truck off with the Heater control to OFF, cold.
Remove the coolant and WS reservoirs' bolts (pretty sure the air filter box may have to come out first), remove the cruise servo from the fender (one bolt), then remove the blower (takes a little force against the squirrel cage). I think the top of the fan has to clear first, but you do have to "force it" gently.
You can run the blower while removed, for a balance check.
Pull as much debris from the corners of the plenum as you can with your fingers, then flush it out with the garden hose. There'll be a ton of crap in there. Verify your drain is open.
I changed a blower motor on an 01 Taurus recently and it didn't come with a squirrel cage (the fan part). It had gaulled bearings and made awful noises when it ran (intermittent). You have to note how far onto the fan shaft you put the cage on, so watch that if you have to buy a new motor.
2000 2.5 MO5D 4.10 one-wheel drive DD - gave to my older son
1990 STX 87 2.9 going in.....Junked it
2000 3.0 4WD M05D 4.10 S-cab Off-Road package with 235-75-15" tires, hotrod DD, lol