Sounds like your timing chain broke! Have you actually pulled the valve cover off and looked yet?
Timing chain
All of the Saturn 4 cylinder engines used a timing chain. The V6 Saturn's used a timing belt.
2004 saturn vue v6
The V6 Saturn used a timing belt. The 4 cylinder's used a timing chain.
Chain
It has a timing chain.
It has a timing chain
All Saturn 4 cylinder engines have an internal timing chain. All Saturn V6 engines have a timing belt.
Timing chain
All of the 4 cylinder Saturn vehicles used a timing chain. Only the V6 Saturn's used a timing belt.
All of the 4 cylinder Saturn's used a timing chain. All of the V6 Saturn's used a timing belt.
A timing chain, that needs to be replaced, can cause your engine to run rough and lose power. A broken timing chain can cause significant engine damage.