I've been working with the longbow (58#@28")and everytime I think I've got it shooting great it seems like the next day it's all out of wack!  I've bare shaft tune my arrow with point weights from 125-250 and with 200 grains up front the bare shaft and fletched ones are hitting together so I figured that was what I needed.  Now it seems the arrows that where shooting good yesterday ain't flying worth a crap today.  Seems like I have one big tail slide to the right (RH shooter) almost all the way to the target.  No wobble back and forth but just want to fly sideways.  Could it be my release?  Whatever it is, I'm so frustrated that I want to use the bow for a weed wacker.    

Very likely could be your release or some other form issue.  Most of us have bad days, and when they come it's best to just lay the bow down and try again later or some other day.  Eventually the good days outnumber the bad.  

Try to just work on one thing at a time.  Release, alignment, pulling through the shot, etc., etc.  It will come together!  

That is kind of funny that you mentioned that because that same thing just happened to me the last time I shot.  Could it have possibly been the wind?
I am going to watch this one.

Is your string new?
It could be stretching on you whether it's new or not.
Try leaving it strung up for several days or weeks in between shooting it.

Keep checking your brace height and nock point position.

And when shooting, hold your form till after the arrow is in the target.

sounds like a form issue-probably with your grip>

sl