If temp was higher at idle, then went down when driving the fan is the issue
The fan's sole purpose is to pull air thru radiator when stopped or moving slowly
When driving, the speed of the vehicle forces air thru radiator, no fan needed
Fan clutch operates based on Radiator temp, on its front is a bi-metal spring that is heated up by warm/hot coolant flowing thru the Center of the radiator
As the spring warms up it expands, uncoils, which closes valves inside the clutch
Inside the clutch is oil
The water pump pulley spins the shaft inside the clutch, if valves are open the fan will spin but not at the same speed/rpm of the pulley and won't pull in much air
As radiator heats up valves start to close and fan pulls in more air and then more air, based on Center of radiator's temp as it warmed up
Simple test for fan clutch
Cold engine, sitting more than 5 hours
Open hood and try to spin fan, should be hard to spin, barely moves, this is called "cold lock" because oil is cold
Start engine, should HEAR the fan moving air because its Cold Locked, but within 5 to 10 seconds it should quiet down, its now unlocked, free spinning
Shut off engine
Spin fan again, should be easy to spin, unlocked
If cold lock and unlocked spin the same the clutch is bad, most likely
But go about your daily driving, and when you get home, engine and rad warmed up, shut off engine and spin fan again
Should not spin easily, warm locked
If its easy to spin replace fan clutch
BUT............first test radiator, remove the 2 bolts at top of shroud, and move shroud back
Run your hand over radiator fins, should be warmer towards upper rad hose then get cooler as you get closer to lower rad hose, and NO COLD SPOTS, you will feel cold spots
If center of rad is cold then clutch may be OK, radiator is the issue, blocked tubes in the center
If you do not have a shroud, then that's the problem, get one
Shroud allows a working fan to pull air THRU the radiator instead of from the sides
So same symptom as a bad fan clutch BUT the clutch would test as OK
Manuals and automatics used different shrouds, because manuals often use single core radiators and autos always used dual core
So shrouds are different depths