its probably the neutral safety switch, they get gunked up and then your jeep will start intermittently and eventually not at all. Your backup lights not coming on is another good indicator of the neutral safety switch needing cleaned. Both of my jeeps started having the intermittent starting problems and within a month one of them would not start without a screwdriver, but after cleaning the nss they both start perfect everytime. It only takes a couple hours and is very easy to do, there are a few different writeups online with pictures and everything