Sometimes, at random, when I'm idling (without A/C on) the car will all of a sudden drop
to about 700rpm and briefly shake or quiver and then pick back up to about 900rpm (normal idle).
Its almost like the car is about to stall but gets out of it. It does this all by itself - I'm not touching
anything. I used to own a 2000 Civic Si and I don't remeber it doing this. I'm totally lost as to
what could cause this.
Any help would be appreciated.

 

Take a look at these:
https://www.s2ki.com/forums/showthread.php?...?threadid=79137
https://www.s2ki.com/forums/showthread.php?...?threadid=88959
Any of it sound familiar?

 

Perhaps the A/C compressor or fans are turning on causing more of a load on the engine??

Is the A/C on when this happens?

Chris

 

He said it wasn't.

 

Check plugs