Overheating can be coming from the pipe/pump sizing aspect of the system design.
Unfortunatley its the only type of overheating issue I have ever really had.
Consider sharing your pipe pump sizings run lengths etc and I bet you will find a few things to improve.
80’ of PEX A running to basement and thru 40 plate heat exchanger. B&G NR22 circulator with a bronze Y strainer before the circ.
Here is a pic of the setup in the basement.