2017 MacBook Pro Unstable on Mojave, Catalina, Big Sur, Monterey..rtf

I don't know even where to begin having been an Apple customer for 22 years. 

I have never seen anything like this and neither have the technicians at Apple Store Watford and multiple Level 2 support technicians in Cork (at least 15 different people over an incredibly stressful 8 week period).

I have erased and clean installed using new user accounts for all the OS’s in my subject heading above, 6 or is it 7 times? I started by going straight up to Monterey and giving up and going back to Big Sur and then finally back to Mojave (thanks to Watford Apple stores help today) but nothing stops the instability… Examples further below.

Background: I was running at v. high CPU’s because I thought it was trading s/ware I had started using (ProRealTIme s/ware) and didn’t realise the high running fans were actually not due to PRT’s s/ware and the large number of Safari and Chrome trading windows (35) being open (typically sites using live java price feeds).

The Level 2 support tried to address the instability on Mojave (which I was on until Feb 2022) before we realised the CPU was spiking up to 500% for anywhere from a minute too much longer. The fans were checked and found to be clogged and dirty. After they were cleaned Watford accidentally forgot to wipe their master user account and I had endless permission issues accessing two external Seagate drives. Three L2 techs couldn’t fix it so it was erased and upgraded from Mojave to Monterey but instability continued.

Instability Examples:

Playing music videos on YT, the sound preferences would be on headphones (to a Kenwood amp/spks), but would change and start outputting through the spks of my TV monitor plugged in to my Mac?

Open Mail and select an email but the email doesn’t read from left to right but top to bottom in a tiny 1cm column?

Create 30 + iCloud mail folders, spend two days manually importing in 10’s of 000’s of emails with L2 help and in which I saw them correctly populate the folders (accountant/banking/trading etc) in the iCloud mail. On the third day I opened mail to find half of the folders were empty and that 47,600 emails had all been sent to a recovered folder at the bottom of Apple mail app?

Log into Safari iCloud . com, go to mail (having been on Monterey and downgraded to Mojave), select an email but the email will not load. None will. Go straight to Chrome iCloud . com and they load? 

Various permission issues with things like Preview where I have edited an image and when I try and edit it again eg a few days later and it tells me I don’t have permission and to duplicate? This despite Terminal: diskutil resetUserPermission / ‘id -u’

Set an image of Hawaii on Desktop 1 (I have 5) and then find it’s gone and its the generic Apple image, multiple times?

I mean the list goes on, slow load for Activity Monitor so it’s all white for second or two before it loads. Prior to overheating AM opened and showed all activities immediately on launch. 

The technician at Watford tried erasing in APFS, then erasing in Mac Extended Journal and then back to APFS before clean installing today but Mojave was unstable as soon as I got home: The sound preference changed (which it’d had never done before in the last 8 weeks of instability), Issues like: Log into Safari iCloud . com and can’t access email letter content. 

The technician also wondered if the iCloud a/c is also causing issues, particularly after the 47,600 “recovered” email issue?

I am at a complete loss and of course being self employed this has greatly impacted my ability to work.

If any experienced Apple users have any ideas I am all ears because frankly the only thing I can think of doing is getting anew computer and starting all over again with a new suer and iCloud account.

Thanks very much in advance for any help or guidance.