Overheating at Idle Speeds Only

Hey guys,
So the other night in the drive thru, the water temp started to rise on my truck as I sat waiting for my food. I put it in neutral and raised the RPM's a bit to try and get more coolant flowing which ended up working and lowered the temperature back to normal operating temp. I'm trying to pinpoint exactly what needs to be fixed but my suspicions are the fan clutch, water pump, or thermostat. Here's what I've done to try and diagnose it thus far:

Checked coolant levels (within normal levels)
Spun the fan with the engine off: It stops after 2-3 fins go by but does not continue to spin
Watched the fan after turning the engine off: it continues to spin 1-2 seconds after the pulley stops
Attempted to hold the fan with some rolled up newspaper but it is driving the fan hard

Checked all the belts and pulleys which are tight and all spin as they should

Upper and Lower hoses from radiator are warm at operating temperature but the lower hose seems much warmer which makes me suspect the thermostat

Watched for circulating water or bubbling in the coolant reservoir but there was none so im not suspecting air in the system but perhaps the thermostat is stuck?

Any info would be much appreciated. Thanks, Jason.

 

is the shroud on the radiator?

 

yes

 

Check the fan, thermostat, etc first. However, your radiator may be on its last legs. That is its clogged and can only adequately cool with high air flow.

 

Are the fins of radiator clogged or bent? Doesn't take much dried mud to reduce air flow through it.

When engine is cold, spray water from front and look to see if it passes through and if it come through clean. I had mine look ok dry but water passed through very muddy.

 

check the AC condensor for blockage. Can you see the tops of the tubes in the radiator? I have a posting called "Radiator basics" which shows what i am trying to explain

 

Yep i agree the above 3 posts, primarily air flow. Although I did have one time on a S-10 overhearing all the blades were wore off the impeller on tha water pump.

 

Link for ease: (I was curious and hadn't seen your post before, great info in there)
https://www.tacomaworld.com/threads/radiator-basics.603387/