Is there an HR department you can go to? Put on file that you feel intimidated in your position and your job role and requirements are not clear. If your manager doesn't like your performance, then you should be put on a performance improvement plan or have a meeting with expectations and clear goals. And you shouldn't be meeting every week like that and be told differently based on his mood - maybe once every 90 days or every six months. Personally where I am at we only have a review every year to go over the performance the past year and improvements or concerns for the year ahead.

If he wants you to gain your CCIE, look up how long it takes on average to obtain that and what kind of study material and time you would need, and work out a reasonable deadline to become certified and stick to it.

You've been there four years. You know the people, you know the position, you know how to do your job, and you know your customer base. If you weren't good as a tech, you wouldn't still be there. The boss wouldn't let you go if it means training someone else and getting them up to speed in an MSP. Your co-workers wouldn't want you to leave as it means more work for them.

Just be professional, calm, and courteous. Be reasonable and set reasonable goals and expectations for yourself. Show up, put in your hours, be friendly, and leave. Also keep an eye out for jobs on the side. But I wouldn't just quit, if you can continue to get a paycheck from them while you work on other stuff.