working with the swing you already have - try and stay loose this is main thing i think of before i step up to the ball - when you practice this you get tremendous speed, loose muscles are fast - perfect example is looking at 100meter sprinters they always look to get loose before settiling into the blocks but they are also pumped up for explosive power.
Make sure you hit up on the ball and use the correct loft - i know you have heard this before
BUT the reason many people hit 3 woods as far as drivers is due to bulge and roll on club face of driver, they are contacting ball too high on the face increasing effective loft and assume that is how far they hit the club - the fact is they may have changed their 9 degree into a 12 and hit the best drives from too high up the club (not sweet spot)
this means that distance is being lost as the sweetspot on a driver is a pinprick and deviation away costs power so in the example above if they got fitted so they hit correct part of club with 12 degree driver the ball would go significantly further.
NOT KEITH