Really don't know what the problem is

[creator]

So I have a 2011 Chevy aveo around 81k Miles. A few weeks ago it would stutter while in 5th gear and the check engine would flash. So after doing some research I was told it was probably the coil pack. So since the milage is at that point I did a tune up as well. The car seemed fine for the last couple of weeks until today when it started doing the same thing again. The check engine light never stays on long enough to leave a code in the computer. So I don't know what the problem could be. It is random when it does it and doesn't do it all the time. I just don't think the coil pack I just changed is bad already. Anyone have any suggestions on what it could be?

[exodus0784]

Define tune up.

[creator]

Define tune up.

Plugs and wires

[creator]

I should say spark plugs and the coil pack. I'm trying a fuel cleaner and High grade fuel for one cycle to see if it will help

[avguy]

Best thing to do would be get a data stream capable code reader or torque app and keep it plugged in all the time. That will let you see the code when the misfire occurs, and also some important things, such as fuel trim. Another easy thing you could do is gently push every wire and hose you can reach while idling, in order to see if you can duplicate the misfire and find the source of the problem.