I have an uber slow swing with club head speed just above 100mph. I can NOT play with a R flex which is recommended. I have very "busy" hands at the bottom. I use the Adams 9064LS with RIP red eye shaft. People always tell me before seeing me hit it that the shaft is too much for me because Im tall and lanky. However I am more consistent with this driver than any other driver Ive hit. It is my theory that the stiff shaft allows for less club head movement at the top where you "load" your swing.
Try this, ALWAYS ALWAYS keep your left elbow stiff. Also make sure you are not swinging outside to in, these are two common mistakes made by people who fight the slice.
Also line your feet up straight at the target, aligning your feet left opens your hips up which will make the slice worse.
Lastly make sure your knees are staying flexed, people have a bad tendency myself included to lock their right knee on their back swing this kills all lower body movement. Keep them flexed and finish on your right toe with your belt buckle facing the target line.
With a little practice working on keeping your lower half consistent and solid, will ultimately lead to longer straighter drives. This is coming from someone who hits nearly every fairway!
cheers