Hey all, I just signed up here and I've had my 300 for about a year and a half now and about 6 months ago I got a check engine light for P0300 and P0303. It wasn't affecting my car at all but I changed the spark plugs just in case. Since then my engine knocks at RPM under about 2000. Above that it drives like it should, ive checked the fuel injectors and have run cleaner through the engine to no avail. My friend thinks it can be the throttle body getting stuck at low RPM's. Anyone else experience this, or have any solutions?