Will turn over, but not start.

I have the 2000 Chrysler Sebring Txi Convertible (with Limited package), with only 85,000 miles. Always garaged and in excellent condition, I bought it recently and had it checked out and it got gold stars. I have put about 2,000 miles on it with zero issues over the past month, where before it had sat in a garage for about three weeks. I recently moved 800 miles away from where I bought it and I split my drive into 5.5 hours and 8 hours the next day. After driving it for the 5.5 hours straight, it sat overnight and was completely fine to start the next morning. After driving it the 8 hours the next day, and then letting it sit while I got settled in my new place (for about 36 hours), it now will not start. It will turn over, but not go all the way. It did downpour and is more humid here than where I came from, if something isn't sealed all the way could that cause problems? I would like some advice before I jump into an expensive repair as I have limited resources. Does this sound like a fuel pump? Spark plugs? How do I tell if the fuel pump relay is bad without a voltage-meter? Should I just replace the (cheap) fuses and relays and see? Thank you.