I have been dealing with an elusive CE light and some shaking of my car for a while now.
For a while it was just shaking occasionally, I thought it was a moisture problem, but that doesn't seem to be the case. The car is a 2005 Mazda M3. I read that these cars sometimes come with a defective engine mount that is too soft, and this looked to be the case to me. The CE light was coming up as intake runner control and also an o2 sensor, but my mechanic didn't think these were the problems.
Recently it started some new behavior. Every morning for the past week or so, my car will stall once, then start fine the second time. Except this A.M. it started fine. The check engine light came on a few days ago, but has since went off. I realized that this started the morning after fueling up, or at least I think. I fueled up at a gas station that I don't usually go to but started going to recently for convenience purposes. My fuel consumption has been horrible, I'm already almost empty again. It's a fast track, which is a fairly large chain, so I thought I could trust their gas. Would bad gas cause the stalling or misfires?
If not, could a problem with the fuel system itself cause stalling or the shaking? The shaking isn't only when idling, it's when the car is warming up. Even when I'm in 4th gear it will happen as it's warming up.
How can I even find out what type of gas I should be using for this car (I got it recently, used)? I have been just using regular, could this cause it?
I can't get it into shop for another week