Before changing the plugs I had a service engine soon light on. The mechanic told me I needed a tune up. Changed the oil, changed the air filter, and continued to drive the car because I was told it wouldn't effect how the car drives. Never had an issue. Last night I have the spark plugs changed with vehicle specific Pulstar spark plugs and cleaned the battery terminals that looked like they needed it. Afterwards, started the car and the service engine soon light was no longer on. Drove the car around the block a few times, no issues. Went home and went to bed. This morning started the car, no problem starting. Let it run for a couple minutes while I fixed the clock and the presets on the radio. Left to drive to work. The car drove fine for the most part, maybe the slightest of shake at one point. About half an hour later, I moved into the left hand lane and had to almost stop completely because of traffic. At that point, all the dash lights came on and the car died. I turned the ignition and it started right back up and drove with no problem the rest of the way (about 15 to 20 minutes). The service engine light never came back on. Is this something to be concerned about or is it normal after changing the plugs?