MacBookPro11,3 - kernel_task 600% when plugged in to External Display

I have seen this topic come up so many times - and nobody has been able to come up with a satisfactory answer for this problem.

I own a Mid 2014 15" Retina MBP running Mojave 10.14.6 - and it's a dandy little machine as long as I don't try to plug it into an external monitor (which is hard, since I'm a web developer and I often need the use of two screens).

The moment I connect an external display (any, I've tried 4, via DisplayPort and HDMI both), the computer hangs up, becomes unbearably slow and quite hot, and kernel_task shoots up above 600%.

Yes, I know that "kernel_task" is doing its job just fine when it reaches 600% - but it's pointing to a deeper problem that is why can't my $2,000 supermachine handle the demands of a basic 2-monitor setup? Or even 1 external monitor setup? What is it that is causing the machine to so demand system resources when all I'm asking is for the GPU to lift a little more weight?

Here is what I've tried:

• Reset NVRAM

• Reset SMC

• Unchecked "Energy Saver > Automatic Graphics Switching"

• Unchecked "Mission Control > Displays have separate Spaces"

• Removing the bottom plate and cleaning out the fans with a can of compressed air.

No, it doesn't matter if the lid is closed. Slows down anyway.

No, it doesn't matter if it's plugged in for battery life or not.

No, it is not a "solution" to just not use an external monitor.

I am so grateful for any help I can get that doesn't repeat the same talking points from other posts - nothing suggested anywhere else has worked!