This may be an IOS 7 issue...as ive only had the issue after I installed IOS 7. I have about 1200 items on my iTunes. Well when i plug my iPhone 5 into itunes it states i have about 20 songs on my phone which is what i want it to have...its what i had on there before I upgraded. When i plug it into my car though a USB in order to listen to it though my radio....ALL my songs play. I dont want all my songs to play as I have childrens music and other stuff that I dont want on random. Hope this makes sense. Im sure there is just a setting that Im missing.