2000 Jeep Cherokee Grand Cherokee - Problems starting

I have a 2000 Grand Cherokee. Last night, the engine would not start. It would turn over, but wouldn't start. After 10 to 15 attempts, the engine finally kicked on and I was able to drive it home. I turned the engine off, tried to start it and again it took 10-15 cranks for it to kick on. I noticed the battery terminals were corroded and the wires to the terminals were kind of loose, so I took it to Autozone. I bought new terminal ends and had them check the battery and check the car to see if it was throwing any codes. Both tests showed no problems. When I put the new terminal ends on, it started up right away, so I figured problem solved. However, I noticed that there was a signifant puddle of oil that smelled like gas where I had it parked. Today it started and ran fine, until tonight when again it took 10 or so cranks to finally start. I'm wondering if the puddle was caused because I flooded the engine when I was trying to start it. Also, what's causing the engine not to start. Should I trying changing the spark plugs? Thanks.