Engine physically shaking and rapid clunking noise coming from engine followed by stall?

After trying to leave my girlfriends house tonight, my 1998 ford explorer Eddie Bauer edition (4.0L SOHC) started up, but surprisingly sounded like a diesel almost in the way that it idled. I had my gf start the car while I looked at the engine and it was physically shaking pretty irratically. Also, a stronger than normal smell was coming from the car. I do not know what this could be...my fluids are all good. But 2 days ago, my car took FOREVER, I mean multiple key turns lasting longer than 10 seconds each. That probably wasn't very good for my car, but I wasn't thinking. I started it 3 times since that occurrence though, and it was fine those attempts. It may have been due to me only having a gallon of gas in the tank and parking on around a 5% grade (the front of my car looking downwards.) if anyone could diagnose this problem with all of my jumbled symptoms, it would be GREATLY appreciated. Thanks so much