there's a glitch in the game where you don't need to kill the at-at that's first attacking the at-pts. I found it out cause it's my favorite level in the entire game (cause it's so hard, and there's ALOT of enemies), go and kill the first AT-AT you see, then fly over to the at-at by the shield generator. MAke sure that you NEVER see the at-at that's first attacking the at-pts, or it will kill them. Once the second AT-AT is down, just fly in circles over by that barracks until the wall has been destroyed. once the wall gets blown, all you do is count to say...20, and then head over to kill the
tank droids that come over the mountains
. If you don't have the Advanced Blasters from Taloraan, you're very screwed in this level, so if you don't have them I highly suggest you get them, otherwise you'll not be able to take down the
fast enough. The Advanced Blaster powerup is on Taloraan, at the end, in the center of the 'cloud city', good luck getting it.
The fastest way to beat the level is by flying straight to the AT-AT that's attacking the AT-PTs, and taking it out, then the AT-AT by the shield generator, then the AT-AT in the middle of the canyon.
When taking down an AT-AT, make sure to only use your left or right brake (depending on which way you turn, i usually turn left, so i use the left brake) ALSO, you'll want to be going as fast as possible, touching the brake whenever you make a turn.
Hopefully this helps.