Today as I was backing out of my driveway in my 11 OS the SES light came on, took it to auto parts store to get code read, came back as multiple misfire (p0300).

Anyone know what might be causing this? I have a 11 manual OS with 55k miles.

 

Some culprits (from simple to expensive):
1. Bad gas - Too much ethanol which could cause moisture in the fuel.
2. Bad spark plug(s) [or the coils that fires off the plugs]
3. A rip in the intake tube/snorkel
4. Malfunctioning/Failed MAF sensor. (it could just be dirty, so you get CRC MAF Cleaner and clean out the sensor, just be extra careful when spraying!)

These are just a few off the top of my head.

There obviously could be other more involved causes/failures.
If you haven't done any basic maintenance, I'd say start there and get those done. IE: change spark plugs, air filter, oil/filter change, etc.

Keep us posted.
Good luck.

 

I thought sparks maybe, but code went away and hasn't come back since, I'll be swapping out plugs next week since I'm at 55k miles.

I know on the evo this used to happen often when over throttled.

 

Do you have the "Freeze Frame" data for this code? I get this code from time to time. My X is much more modded and tuned on e85. If the e85 changes slightly it'll set this code off because my LTFT is maxed.