89 pickup. 22re. Replaced water pump 3years ago. ( it massively failed the impeller fell off and the fan was spinning off axis). I have been having issues with it running hot since last summer. Both times I just took out the thermostat. I am currently running with no thermostat. Last summer it would run hot when I coasted down the canyon. It would cool off when I put it in gear and ran the engine at higher rpm’s. This year exact opposite is happening. I put it in gear and start driving it heats up and when I press the clutch and take it out of gear it immediately cools down. Any suggestions would be appreciated. This is my daily driver. Thanks

 

Maybe liquid coupling aka fan clutch is bad?
Comparing Good and Bad Liquid Coupling would not cost you a penny:
https://www.yotatech.com/forums/f199...l#post52229129

 

Also, check your top radiator hose. My friend had the same problem only to find out that at higher RPMs the top hose was collapsing shutting off the coolant flow.

 

Just a thought. With all the on and off of parts - did the system get completely burped each time?