Tonal, I know you've benn having this issue for quite sme time...
.
Have you tried reducing your pinion by 1-2 teeth? Do you see any improvement? With a 20T you get a FDR (Final drive ratio) of 10.22, which might be a bit high for a 6.5T... But also, that depends on your track and driving style...
I'd also check your temp gun with someone elses just to make sure it is accurate.
Have you installed a fan/heatsink on the motor? definetly worth a try as it will save you a few degrees.
Good luck!