Intermittent SES Light... ?
 

Hey everyone. I have a 2006 Infiniti G35 Coupe (Base Model) 5AT. About a month or two ago my check engine light came on while driving 35 miles to work. It was on again when I went back home. Then, the next day when I left for work, as I merged onto the interstate it turned off.

Fast forward to today, the problem came back. I doubt it has anything to do with this, but I had my brakes and oil replaced/changed and then the next day the CEL came back on while going to work. It was on while going back home, so I stopped at the place I got my car serviced (Firestone Complete Auto Care). They said it was a "Large Evap Leak" and said most of the time it is from a loose gas cap. I did just fill up the gas after the brake job and before the CEL came on so I was like ok. They redid the cap and reset the light. It came back on 30 minutes later. The next day, it turned off while merging onto the interstate again. It came back later that day after I got home and went out to eat. It once again turned off while merging onto the interstate today and hasn't come back on just yet.

I am wondering if the movement/inertia from taking the onramp at ~75mph is adjusting something internally?

Any ideas how to determine if the problem is the gas cap, or like a hose, or the evap filter or something else? I am not too happy about spending a ton of money after my expensive brake replacement.