Hi Tiger. Here is some unsolicited, free advice from Herb.
You have been trying to fix your swing with a serious of complicated mechanical adjustments, which work on the practice tee, but are virtually guaranteed to fail you on the course during tournament play.
Let’s start by admitting where the problem started. When you were younger, you had just about the perfect physique for golf. You went through a strength training regimen, adding much more muscle than your frame was designed to accommodate. Along with the added pounds of muscle, came added strength, which led to swinging harder, which in turn led to back problems. The mismatch between your basic frame and the added muscle only adds to the problem, and makes it much easier for you to hurt yourself when performing non-golf activities as well.
Your “fix” does not lie in changing your swing mechanics. All these changes have done for you is add confusion, and short-circuit your inherent, natural talent. Your “fix” lies with rhythm and timing.
Here is a Herb trick for regaining your rhythm and timing. Get a driver with either a regular flex shaft, or even a senior flex shaft. Swing the club back, imagining that you can feel the shaft bend at the top of your backswing. On the downswing, concentrate on swinging at a pace that the shaft returns to being straight, exactly at impact.
That’s all there is to it….just add trusting your natural ability.