Misfire and rough idle?

I have the car listed above S. It has begun to have misfires. I received an oil change at the dealership at end of last month and 10 days later my engine light and traction control light came on steady. The VCS Off light also came on and was flashing. I began to notice my car was starting was rough. I changed the battery, coils, spark plugs all with brand new parts. I continued to get misfires in my cylinders. I had my fuel injectors cleaned professionally and continued to have the misfires in all cylinders along with a p0300 code. There is a small tick noise coming from the engine, startup it idles very slow and sometimes stalls. The car seems fine at anything besides an idle and the tick goes away when higher RPMs. I checked my MAF sensor, and it seemed clean and I didn't mess with it beyond that. Please help.