When I start to play bad, this is my "go to drill". I got this from reading Sam Sneads book (don't remember the name) but he said when he had tempo problems, he would hit one or even two clubs more into greens. For example, I have had a couple of crappy rounds recently. I went over to the course the other day (afternoon) when the play slows down and hit a couple balls with a club more (150 yards, usually an 8 iron, I would hit a 7 or a 6). It helps slow my swing down as well as lightens my grip pressure and also helps me to make sure I'm keeping my head from moving all over the place. Give it a try and see if it helps.