1997 Nissan Maxima Will not start up

Have you checked for fuel or spark? If not check if it has spark, simply unplug a spark plug wire and put a screwdriver in the end and put close to metal and crank is there spark. It there is spark then you will need to see if there is fuel. Here I would get some throttle body cleaner and spray it in the throttle body and see if it starts. If it does then I would check fuel pressure as it may be the fuel pump, this would also explain the hard starting prior to this. Let me know what you find.