"I'm fine with my irons... maybe not quite as good with the longer irons... but I absolutely cannot hit my driver... somebody help!"
Does this sound like you?
Let's Get Technical
A lofted short iron creates a proportionately high amount of backspin compared to long irons and woods. Distance decrease dramatically due to the high degree of loft & lack of side spin allows a golfer to hit a ball pretty close to a target with precision.
On the contrary, a longer shaft will increase the club head speed, reduce the amount of spin-control, and widen the golf swing - allowing more room for errors. A poorly aligned club face on impact will push or pull the ball off line and result in a shot thats most likely ends up in the rough or hazard.
Summary: short irons allow for more error, but are easier to hit; long irons and woods amplify any swing faults and are more difficult to hit.
Most people instinctively feel they should swing harder with the long irons and woods because they want to maximize their distance. The ball should go further, but you should not swing harder! Each club is designed for a specific distance and purpose. Having less loft will result in a lower trajectory and a ball that will likely run further. It's important to remember not to change your swing according to each club, but rather to relax and let the club do the work for you.
Lacking confidence on the tee box is a disaster waiting to happen. Fear and doubt that builds up before a shot will leave you over-analyzing the situation and often lead to poor execution. If you haven't realized already, teeing up with your driver and praying for nothing bad to happen isn't the best game plan! Until you work out the problems you are having with your driver, try using a 3-wood or hybrid as a replacement.
The next step is to get some reps in and don't swing too hard on those long irons!
Soon enough you'll be on your way to hitting that driver down the middle of the fairway like you've always wanted.
See you on the greens!