Get a cooking thermometer or something similar and check the actual heat output so you have some frame of reference.
The FSM for year 2000 says minimum heat output on high at the floor vent should be 144 degrees at 60 degree ambient air temp.
Once you figure out where you stand, you might be able to see what helps, rather than just a "seat of the pants" analysis.
Also, if you look at the blend door actuator (under dash on passenger side) you can actually see the motor turning while you manipulate the heat control. If this works, it could still be some type of linkage inside that is malfunctioning, but at least it gets you one step further.