2000 civic lx, 69000 miles. 2months car suddenly idled very low (100rpm) all the time& check engine light came on. Code said o2 was bad. Changed top o2 sensor, disconnected batt to clear code, everything fine for a few weeks, then the low idle again, but no check engine light. Drove for 2 months like that, with low idle at least half the times I drove. Then car started " surging" while driven. Light came on, code says cylinder#4misfire/random misfire. Sure enough 1 of the 3 distributer cap bolts snapped off causing a small gap ( cap wasnt seated all around). Replaced bolt, disconnected battery to clear code, now car idles low, surges while driven and no check engine light. Car will idle low with a/c on as well.
also, sound like a bird chirping coming from engine area but occures when idling (mostly low idle) and in unisome with bumps in the road. PLEASE HELP! : (
The chirps should probably be belt related. Check the belts for wear. The surging problem, does it happen all the time or only when cold or warm? Check vacuum leak and this includes the intake maniforld and manifold gasket.