Hey this weird thing happens when I turn on my car. The cars an 89 CRX SI. The car idles at around 2000 for a while, but when it warms up it returns to its normal idle. What could this be from? Also on its normal idle the car shakes, should I go ahead and set the idle a little higher? Its idling around 750.

 

My Civic 90 DX was shaking pretty bad while it idled. Replacing the fuel filter seemed to fix it.

 

Ummm... how long have you owned this car? The car is supposed to idle at ~2000 rpms to warm up the engine, and then return to normal idle once it gets there. Sounds normal to me.
As for the shaking, that's strictly an RPM thing. Sometimes your car will stop virbrating at even LOWER RPMs. My car will shake if it's at ~700 rpms, but at 500 rpms it purrs nicely. Anything below 500, though, and it shakes again.

 

Ive owned the car about a year and it started this warming up thing only in the past month.

 

my 89 civic does the same thing and i just had the motor rebuilt so it sounds normal to me unless when you have the clutch in and goes up to 2000 after its warmed up. if thats the case try checking for a disconnected hose under the hood.

good luck