Go back to 195deg thermostat, better for engine and better for you, best MPG with 190-195deg t-stats
A working thermostat has nothing to do with overheating, using a 180deg or a 195deg t-stat on an engine will not change anything if there is a cooling system problem.
That 15deg difference is nothing if cooling system has a break down, overheating happens fast on a breakdown.
But long term the 195deg t-stat will make for cleaner oil, good for engine life, and better MPG, gasolines conversion to energy is more efficient with coolant temps above 190deg.
Both these facts are from SAE(Society of Automotive Engineers), yes mostly known as the "oil guys" lol
Pull out the heater core, 4 screws and 2 hose clamps, very easy to do
Look under glove box, there are 4 screws, I think 8mm heads, 3 are at 3 lower corners facing up, one is at last corner but higher up, you can see it if you lower glove box door all the way.
Put a towel down as some coolant will spill out as you angle the core to get it out
Flip core upside down(outside the cab, lol), all coolant should drain out, core should be very light then, shake it, if you still hear coolant inside or it still feels heavy, core is clogged up, replace it
Heater core is the cooling system by-pass, as it gets clogged up coolant temp will go high and then back to normal, for no real reason.
While heater core is out check Blend Door operation
It is cable operated in 1993, the COLD-HOT lever on the panel
In cold position the Blend Door Covers the heater core so no air from the fan can pass thru it, by-passes heater core
In hot position ALL air from the fan passes thru heater core
In between positions Blends the cold and warm air to set cab temp
Cable runs to the top of the air box, with glove box down all the way you can see the cable and how it changes Blend Door position
Put your hand up in the air box while heater core is out and operate Blend Door to make sure it is moving and opening and closing all the way.
If any engine starts to get higher coolant temp at lower speeds or idling then most likely cause is Fan Clutch, could be water pump but usually Fan Clutch.
At faster speeds the fan is not used, vehicle speed causes enough air flow thru radiator to cool the coolant as it flows thru radiator.
At lower speeds and idling fan needs to provide that air flow.
Fan shroud and fan clutch are important at lower speeds and iding