A tension filled grip, especially from having the shaft too much in your palms, will kill your entire swing. It stops your wrists from hinging naturally and then works its way up your arms and into your shoulders and locks up your entire swing.
Making mini swings with your elbows glued to your body will give you the correct sensation of the large torso muscles swinging the club, not the arms
Cutting your backswing down to a more manageable length can help you control the distance of your shots