So everything sounds good in logic when i bounce it to mp3 an preview it through itunes vocals sound fine but the instrumental sounds drown out and like s*** excuse my french anyone know what i'm doing wrong?
I wouldn't bounce directly to mp3. Bounce to a lossless format first. Listen in a player that doesn't compress or otherwise process the audio. Does that sound okay? If yes then import the lossless file into iTunes and play the file (make sure Sound Check is off). How does that sound?
Are you doing anything to enhance the stereo width of instrumental tracks that you aren't doing to the vocals?
Bouncing to wav of mp3 should not make that much of a difference. The mp3 version may lack some low end power but the problem described can not be related to the format you bounce to. Try to do a real time bounce and listen to the music while bouncing.