Ok well, I have a 95 civic that won't start. It has been sitting in one spot for about 6 months. But it would start up consistently for a while and then it would consostantly not start for a while I thought mabe it was the fuel filter being clogged, so I had replaced it. I put the key in the ignition and everything works as it should. I turn the key and the engine comes on but when I let off the key the engine shuts off. But the weird thing about this is aslong as I hold the key all the way down the engine will stay on but as soon as I let off it the car shurs off. Any Ideas ?

Simple. Replace the ignition switch and harness:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-2.html#post224652