Slow Mac Pro 6,1 and fan runs full speed

My Mac Pro 6,1 just recently got slow. When the machine powers up and gets to log-in page, I realize the fan picks-up speed gradually and the computer becomes slow during boot.

when It first started to get slow I realized this problem was showing up at particular time of the day(usually after5pm).I work from home and usually my neighbors have come how by then. So I was thinking it was related with power quality as at that time the electricity increased in the area. (but I use a UPS APC 1000va) But lately this problem pop up everytime I power up the Mac. I am unable to use it as the Mac runs extremely slow.

I have been running os Monterey for a while now with the latest updates. The hard drive is the standard 500…gb SSD it came with and the d500 gpu’s. Ram is 32gb and until recently the machine had been awesome at delivering every task I give it.

I opened the machine and I saw some durst on the heat sink right opposite the fun. I cleaned the machine with brush and blower.

I have more than half of free storage space. The fans blows loudest like and rendering a video but the air coming from the vent is cool not hot. Kernel_task is at its highest usually over 1200. The machine seems to be working soo hard even at start-up. I did an Apple diagnostic test and it reported a PFM006 error.

Please if anyone knows how overcome this problem pls help.

Thanks