DuckySaysQuack

I have a 2009 C300 w204. Only 55k. In the fall I have been getting strange electrical problems with my car. Once, I put my key in and tried to start and nothing happened. Pulling the key in and out a few times and it starts up fine. This happened like 3 times. I thought it was a battery issue. I got my battery changed at SEARS with an DIEHARD GOLD AGM battery two years ago. I went back and they did a test and said the battery was operating normally. It's two years old and I can't imagine it going out this quickly. This past month I had an odd issue where once I start up and the headlights and dash screens would flicker. After about 5-10 min of driving they would become solid. Then two times this week within the first 10 min of driving I get the entire dash and headlights turning off for a quick second and the car jerking while I'm on the gas like it skipped a spark. After the jerk all the lights were back again almost like the car reset itself mid pull. Yesterday the check side airbags notice popped up after the jerk. I'm thinking this is an alternator or battery issue? Thanks for any thoughts.