The car was running the day before but will not.

The car was running the day before but will not start now. It tries to start, and when I depress accelerator to floor the engine will pop back throught the intake. I replaced coolant temp sensor, fuel filter and have fuel pressure at the shrader valve, have spark on all four cylinders. Before, when the car was running I could hear the timing chain slapping around a little. I removed the valve cover and found the timing chain loose with a deflection of at least a quarter inch. Could the timing chain have slipped a tooth, and if so would the car not at all, even roughly? Just want to know what else to check before going for the timing chain. I appreciate the help.