I think patience is the key. You will drive yourself crazy if you think you have to do everything perfectly from the moment that you are promoted up a tier. I didn't - and still don't do everything perfectly. Probably never will.
Practice and ENJOY honing your game and perfecting your skills to adapt to the new situations. Challenge yourself to take some ENJOYMENT from these challenges. After all - it is a GAME.
My opinion differs from others here - who also hold valid opinions - (take from us what is useful). IMMEDIATELY - Change NOTHING. I do not advocate an immediate change in gear. Adapt your game to the new situations and take your game AS FAR AS IT CAN GO with your current gear. This takes some weeks. Decide where the "holes" in your own game are before you buy gear. And change ONE THING AT A TIME. If the biggest hole in your game is DISTANCE - then that is when you might consider a Driver upgrade. You might be surprised to know that IN MY OWN CASE, I never bought (yet) a "Master Driver" - the biggest "hole" in my own game after a few weeks at Master level turned out to involve my SHORT GAME - and specifically WEDGES. So I upgraded those (in early January). That is now beginning to bear fruit as I have been adjusting them into my game - I have now had my first taste of scoring 30 (2 times) for 9 holes and I EVEN HAD A 29!
TAKE PRACTICE in the form of some Match Play or Stroke Play MULTI-PLAYER rounds and OBSERVE other people from your tier - how do they play? How do they escape from bad situations? OBSERVE THE GEAR THEY USE AND ASK QUESTIONS OF THE PEOPLE USING THE GEAR. Do they like it? What is is accomplishing for them? USE the CHAT function!
The bottom line: IN MY OPINION - You are now playing from longer tees. That is a big adjustment all by itself. Get used to that one thing for right now WITH YOUR CURRENT GEAR. If you change gear ON TOP OF adjusting to the longer yardages, you will have several "moving pieces" - and this can undoubtedly lead to frustration AND a skyrocketing average (which seems to hold importance to you).
Some additional "reading" - other posts which you might find useful:
"Why Have You Not Bought The Master Driver? - My Reply
Playing For FUN vs. Obsession With Averages and Tiers
10 WGT Nightmares: A Pictorial Essay And Discussion - Some Game Tips In Here
In closing - No need to be UNHAPPY with your promotion to Master - it means your game has matured nicely. Enjoy it!
Best Regards, AtlantaCoaster