2001 Silverado will crank over but will not start?

I ran it out of gas and it was driving poorly. It all of a sudden made an awful noise that sounded like the exhaust gasket. Well I changed the fuel pump because the sensor wasn't working anyways. I then installed a new fuel filter. The loud noise was still there. I bought an exhaust gasket and found a plug wire loose. The plug closest to the firewall on the passenger side came out. I installed a new one which was difficult and I see why it came loose because they were too lazy to tighten it right. Now the truck turns over but won't start. I tried starting fluid and that doesn't help. Any ideas. Also I have a remote start alarm and the battery died and set the alarm off when I charged it.