2010 Prius still shakes after head gasket job and EGR + intake cleaning

Sorry it's been a few days. Finally got a hold of the borescope and a coolant system pressure tester. In the video I attached you can find the main issue I'm facing (the violent shaking). Like previously mentioned, the shaking is continuous and doesn't go away as seen at 0:10-0:16 seconds at the start of the video.

I went ahead and plugged the EGR pipe completely off with a flat spade I had. This resulted in a smooth engine idle which I experienced after doing the headgasket and prior to doing the EGR/intake cleaning. There is an intermittent shake that is minor that can be heard at 0:54 seconds. This intermittent shake was the same shaking which lead me to do a deep clean of the EGR system and intake.

My thoughts as of now... I think there might be an issue with my EGR valve. Plugging the EGR pipe with the spade has replicated the condition of the car prior to my deep clean. Could the reason why my car is now violently shaking after the deep clean be due to some exhaust gas being let back, but a blockage somewhere is causing issues b/c inadequate exhaust gas is being sent back to all 4 cylinders? For example, before the deep clean there was so much blockage that no exhaust gas was coming back which is the same as plugging the EGR pipe completely with a spade. Now that it's clean, some gas is able to pass, but not equally in all 4 cylinders?

From the 1:00 mark to the end of the video I show the condition of my cylinders and check for leaking coolant. I pressurized the coolant reservoir with 15 psi which is about the same as 108 kPa which is suggested on the cap. All four cylinders seem to not be leaking any coolant after 30 minutes of pressure. As of writing this reply, it has been about 2 hours since I pressurized the coolant system. The pressure still holds at 15psi and there is no indication of leaks.

tldr: Car doesn't shake when EGR pipe is blocked with spade & runs exactly as it did before doing an EGR & intake deep clean. Coolant system pressure tested for 2 hours and borescope showed no leaks in headgasket.

Should an EGR valve solve my issue? Please offer your expert opinion before I splurge on a new EGR valve.
Thank you so much for your time!!!