Question: Increased temperature lowers viscosity of gases like air but also decreases density.
So then drag force would be lower if an object is thrown in higher temperatures but what about viscosity? I thought viscosity was drag.

Answer: 
Depends on how fast the object is traveling through the fluid a.k.a. the value of the [Reynold's number](https://en.wikipedia.org/wiki/Reynolds_number).

If the flow around the object is turbulent (high Reynold's number) then [density is the key fluid property.](http://hyperphysics.phy-astr.gsu.edu/hbase/airfri.html#c1) If Reynold's number is small then [viscosity becomes relevant.](http://hyperphysics.phy-astr.gsu.edu/hbase/airfri.html#c3)
Viscosity of air increases as we increase the temperature. 
This is because velocity of air molecules increases making the air molecules to collide frequently with the object .
So drag force increases because viscosity increases.