My 2013 Civic has ~48k miles on it...it has been a commuter car, for sure. Recently, I've started noticing a shudder happening periodically when idling. I changed the air filter about 2 weeks ago, and that seemed to help. 2 days ago, I switched to high-octane fuel and put some injector cleaner in it right before hitting the interstate for a 4-hour trip. For the first few red lights after that, it seemed to have worked. Now, however, the shudder is worse than ever and the car seems to be running rough. I can feel it in the gas pedal while I'm driving. I should point out that passengers don't really notice these things happening. If I didn't drive it all the time, I might not even notice that anything was wrong.

 

Which Civic are we talking about exactly?

 

Change your plugs and wires. Or at least have the plug gaps checked, It sounds like your rough idle is from poor ignition or fouled plugs.

 

^ A 2013 has coil packs and the spark plugs are iridium which normally should not need to be changed yet.

 

Passenger side motor mount.

 

let us know what you find out here. I'm curious about this one as it is the same year as mine.