My car all of a sudden started running rough. I actually pulled over I thought I might of had a flat tire. I went to a mechanic which drove my car and put it on the computer and said everything seems good. This guy is reliable. But it is still running rough.
If it is running well now and the diagnostics did not show anything, there is nothing you can do about it except wait for it to occur again. If you had not done any tune-up, have the spark plugs checked and maybe at the same time ensure the ignition coil wires etc are secure.