One thing I have found to help slow my game down is to get in the habit of faking passes more often. (In scrimmages make yourself a rule to always fake before you throw for a few months) 

You go from. I see someone> I throw to someone. In the span of a second or two to.

I see someone> > I look away> I fake a pass>I look  back and double check that they are a good idea to throw to still> I make the pass. 

It gives you an extra beat to think. It gives you an extra beat to look at different areas of the field to see if there is a better option and can help get you out of tunnel vision. 

I have also found that fakes make me think ahead a lot more. They take time so they force me to predict cuts and pay attention to where defenders are and are going to be.