I am unable to get my 94 Skylark to start. It was running fine until the other day. It just decided it did not want to start. The plugs and plug boots were old and dirty so I replaced them. I put fresh gas in the car. There is spark and the starter and battery seem fine. It just cranks but will not fire. We checked the timing chain, it is not broken as the top half of the motor is turning. We also could see the piston moving up and down through a spark plug hole. The fuel pump seems to be working as well as you can hear it working when turning the key. We also checked the fuses to make sure there were no blown fuses that could affect the fuel pump or ignition. I am at a loss as to what is wrong. There were no warning signs to anything being wrong until it decided not to start. Any suggestions, ideas would be appreciated.