1995 Jimmy wont start - Will only start with starter fluid

I have been having problems starting my Jimm y lately in the cooler and wetter weather. I can hear the fuel pump running when I turn on the key. When I turn the key to start it it will crank but it just wont start. I pulled the air cleaner hose and sprayed some starter fluid down into the intake, put the hose back on and the car started right up. After it started it ran perfectly fine. After I shut it off and let it sit for a couple of minutes it wouldn't start again unless I sprayed starter fluid into the intake. Any suggestions?