I had that exact problem..
so you may be in luck if my fix works as good for you as it did for me, it addes about 70-90 yds for me! right before impact about 2-4 inches ( if you are not loose enought and swing properly with your core than it will be really hard to do. but if you are swinging properly and let you arms whip around you like they should do..... then 2-4 inches right before impact and no sooner rotate your right hand over your left as fast as possible. it is almost like resiting the left hand and taking over completely with the right hand and try to twist your arms as fast as posible. it is hard to explain, hope you understand correctly. almost like trying to see how hard strait down your target line you can throw your right hand whilst twisting it CCW. just keep in mind not to spped up your tempo or tighten up, but just 2 inches before impact twist. You will be amazed at what happens!