My heater is only putting out maybe 30-40% of the heat it typically does. I'm not low on coolant, and I have the stock stat. At about 200° and on high it feels luke warm. Any ideas of what to check?

 

If your coolant is hot and your coolant (in the radiator) is full and your heater control **** is working, than we are down to the heater core, which might be partially clogged only allowing a mall amount of coolant to go through.

You might want to flush the heater core and bleed the system to make sure there is no air lock.

When your heater is on full blast, check the inlet hose to make sure it is full and hot.JMHO