The "severe duty" fan clutch is probably not compatible with the stock fan. I'd expect the stock fan to have too-little pitch to the blades, too-little diameter, and/or too few blades--in other words, DOESN'T MOVE ENOUGH AIR to warrant a "severe duty" clutch.
Using a "heavy duty" or 'severe duty" clutch on a "regular duty" fan means the clutch will never properly disengage. It will therefore make too much noise, pull too much air, and require too much power when the engine doesn't need the extra cooling.
220 is not hot enough to be considered "overheating"; the dash warning lights typically come on at 240--260. Modern cars may not turn on the second electric fan until 220. But 220 at the thermostat housing does mean that your thermostat has LOST CONTROL of the engine temperature. That's not good.
I'd be looking at all the usual suspects:
Faulty temp sending unit/inaccurate dash gauge--the sending unit in the side of the head near #1 spark plug is known to be hotter than the coolant temp at the thermostat because it also picks up exhaust heat. Can be worthwhile to point an infra-red thermometer at the thermostat housing--but they have their own problems with accuracy.
Radiator internal condition--scale on the water tubes, low coolant level, rad cap pressure
Radiator external condition--folded or corroded air fins, dirty
Belt and tensioner condition--if the tensioner jiggles, it's shot. Tensioners should have the acceptable range of motion indicated on them. If the belt is worn/stretched, the tensioner can go out-of-range.
A/C Condenser external condition--Folded air fins, dirty
A/C high-side pressure--high pressure = high temperature and increases load on engine
Coolant condition--Antifreeze concentration (too low promotes rusting) coolant level, color (cleanliness).
Ignition timing--initial and timing advance
Fuel supply--running lean including vacuum leaks promotes overheating
Brakes dragging--increases engine load
Trans converter clutch inoperative--increases engine RPM, increases piston travel per mile, increases friction, (but also increases water pump and fan speed, which somewhat offsets) also increases trans temp and that heat ends up in the radiator
Missing/broken air dams, fan shroud, hood/cowl seal
Rusted or damaged water pump impeller
Incorrect water pump pulley ratio
EGR operation
When you flush the coolant, be sure to pull the block drains--there's a steel/iron plug on the driver's side, usually a 9/16 hex head; and the knock sensor on the passenger side screws into the block drain hole. Remove both the plug and the sensor to drain both sides of the block. When it's me, I use a brass draincock in the passenger side instead of the iron plug. Torque the knock sensor to spec with sealant on the threads.
Both drain holes are commonly plugged with debris--rust that's settled to the bottom of the water jacket and has to be poked with a screwdriver or awl to break-through to coolant. If it's real bad, you'll be pulling the engine to replace all the core plugs.
