Why are you thinking about the OB? Whenever our minds start to think about something, all our focus and attention goes to that, which in this case is OB and a bad shot. Look at the fairway and that spot in the fairway 120 yards out where you want to be. You want to hit it in the fairway so start focusing your mind on the fairway!
I have no problems with hitting a club to get into a more comfortable yaradge but if you make bogey at the worst hitting three wood & 6 iron, then why not do that instead of bringing double and triple into play with a hole that has your number? If you're not comfortable hitting a 6 iron from 160 yards, then why not just hit an 8 iron close to the green and pitch it up close and give yourself a chance to make par and bogey at the worst?
I use to have the same problem, hit great chips and flops when the shot was harder and screw up the so called easy ones. The reason was because I focused more on the tough shots because they required something special. When I got over the easy ones I was very non-chalant and didn't take my time. Easy thing to do is just focus more and not think of the chip as an easy shot.
A good drill for tempo can be seen at the link below in a nice video. Something really cool that I haven't seen many people talk about when it comes to tempo.
http://golfinstructionguy.com/wind-golf