My heater doesn't seem to work right on my 85 22RE Pickup.  If I just let
it idle to warm up it doesn't get very warm at all.  If I drive it and get
the RPM's up to 2000 or so it does get warm but never hot.  
The needle on the temp guage goes up to about 1/3 of the way to the red
but never farther.  I tried putting some cardboard in front of the
radiator but that didn't help much until I drove 20 miles or so down the
freeway, at which point the needle did go up almost to the red zone and
the temperature at the outlets did get pretty hot but I was afraid that it
was going to overheat so I took the cardboard out and went back to the
lukewarm air.
Does this sound like a thermostat problem?  I stuck a thermometer in the
radiator yesterday and the water is getting up to about 175 degrees.  
Would a new 191 degree thermostat actually get the radiator water up to
191 degrees and would that extra 15-20 degrees make a noticible difference
in the amount of heat coming from the heat outlets?
Any recommendations???
TIA.
JM