what could be the problem?

I have a 92 dx with about 67k on it... when the car idles the tach is real shakey, like it bounces up and down 50 rpms. It doesnt feel like its really rough, but its a little shakey. Does any know what might be wrong?

sounds to me like you either have a faulty Throttle Posistion Sensor, or a stuck throttle cable.

My friend had this problem with his 96 Eclipse and it turned out to be his his throttle body coughing the air through the filter. He had a stock Intake and Filter, but he just had to run the engine for a minute or so without the Intake on at all. So try taking the intake off completely and then run the engine like that for a little bit. Then shut it off and put the intake back on, and it should be fixed.