One of the possible root causes for those symptoms might be dried up (or wrongly applied) cooling paste between the heatsinks and the CPU/GPU.
I highly recommend trying to replace the cooling paste, this may fix all your issues.
I recently did this on my 2 year old Asus laptop and it feels like I just bought a new machine. It went from unusable to I won't have to buy a new laptop for a couple more years. It cost me 10 EUR and maybe half an hour to get it done.
You won't ever have an issue with dry paste, and from what I can tell the CPU/GPU only runs a degree or so hotter than when using premium thermal paste.
Stock paste goes for longevity and cooling, so it's kinda crummy at both.
Thermal pads go for longevity with a sacrifice to cooling.
High performance paste like arctic silver goes for cooling over longevity; but can be re-applied many times as it doesn't damage hardware.
Liquid metal like Thermal Grizzly's: conductonaught, goes for extreme cooling at the expense of hardware. (IE; it will literally eat your computer, slowly, over time).
According to a Linus techtips video on Youtube the difference is not really measurable. So I kind of tend to think that a high quality thermal pad is just simply superior in every way. The only reason I didn't try it, is because I couldn't find any in stock.
https://youtu.be/YpphKzmDiJM?t=420
FWIW Steve Burke did an even more detailed burn down of these pads:
https://www.youtube.com/watch?v=niAQs8dZohE
(LTT was later able to get -20C cooling with Liquid Metal: https://www.youtube.com/watch?v=hdTsra-uLBI )