Non-USA 14 year old  Standardbred cross ridden on trails & in arena with snaffle, bareback pad, english style intermediate level rider.

Question: My horsegaits easily, but does not carry himself well. His head is always too low and he shuffles along, sometimes breaking into a pace. He trips often, even on a smooth road. He wears regular shoes and  has no problems with his feet or legs.

First, if your horse is doing a lot of stumbling, I would suggest that you  have the farrier trim his front feet with the toes short.  You could either  keep him in the snaffle or go to a mild curb.  I like to use a loose-shanked Tom Thumb type of bit with a snaffle mouthpiece once I take them out of a plain snaffle.  To improve his carriage and get his weight off his front end,  do a lot of halts followed immediately with a back.  Back him a few steps 
and  then immediately ask him to move forward.  All of this is blended together -  not done as separate movements, but blended smoothly one into the other.  
 
You  will notice that for the first few steps forward his carriage will be  improved.  As soon as he begins to fall apart again, and I'm sure he will,  repeat these movements.  Keep at it until he starts to get off his front end  and lighten up for you.  From the back you can ask him to walk forward, or  gait forward, or canter forward.  This will take time and a lot of 
 consistency on your part, but eventually it will make your horse much lighter  and more responsive.
   
 "Good luck" and stay with it!  Remember - he has had many  years of carrying himself as you described.  And also, all horses have to be  taught to be light and balanced.  They are not that way naturally when under  saddle.  It takes time and dedication and it is worth the trouble.
 
Nancy