fwiw: I started hitting booters a few years ago with no instruction, but after seeing the basic SA vids on it, I began doin the whole setup carve and everything, leaving the lip off my toe edge....but I don't have your issues....as you go into the air, visualize where you are headed, straight into the nothingness above the knuckle.
Just saying you can still follow those instructions and go straight. Your problems probably have more to do with incorrect body positioning as SW said.
For a straight air with a setup carve, simply carve so that the lip of the jump is at the apex of the turn, essentially pointing you straight, again sort of hard to explain, but you can have your board on toe edge and still be perpedicular to the lip - this is what you want, but it sounds like you are probably turned beyond perpendicular as you get airborne.
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