Your iron shots lack that crisp, pure feela sign that you're not fully compressing the ball and losing distance as a result.
The Conventional Wisdom on how to fix it
Hit down on the back of the ball.
Why that isn't so wise
Hitting down on the back of the ball is a good tip for stopping thin shots, but it doesn't help you transfer maximum energy to the ball. You won't reach your distance potential this way.
The new (and actually wise) wisdom
Think of yourself as a righthanded batter, with a golf ball sitting on home plate. As you move into impact, try to sling the clubhead toward rightc enterfield. Approaching the ball from inside the target line like thisas opposed to down the target line when you try to hit the back of the ballreates the shallow arc necessary to make centered contact and compress the ball so it shoots off your clubface like a rocket. At impact, your clubface should strike the lower-left quadrant (the one closest to you) of the ball.
Use a paper cup to juice up your ball-striking
The Wise Man's Drill
Mark an X on a paper cup as shown below, then cover the ball with the cup and turn it so that the X marks the lower-left quadrant of the ball. This will give you a nice big target to strike. Make your swing and try to hit the ball under the cup. You've made solid contact if the cup flies straight and low. If it flies straight and high, you came into the ball on too steep of an arc, which means you didn't approach the ball from the inside.