digital servos will make no diff and run down the battery faster, also your gyro doesnt "talk digital" so it wont help there either.
go for the loose crystal or dirty pots in the tx or your antenna. Most likely dirty pots in the tx will make it eithr sluggish or make the servos jump around or not respond correctly.
Take the back off the tx (take out the batteries first) and get some spray contact cleaner from Radio shack and use the little tube to spray contact cleaner into the pots that the sticks go to. Rotate each stick in a circle about 25 times in each direction, then spray in some more to flush it out, this usually cleans up the pots. also remove your crystal it pulls stright out and reinsert it do this with the TX and the rx. I dont know where your antenna is at but you might try running it back through the tail skid and back to the front of the heli (just so it doesnt get caught in the tail rotor).