I just noticed this problem last night, before the car idled just find and didnt shake at all. It still idles at 750 rpm, but shakes badly. I noticed if I rev up the engine a bit or start moving, the shaking lessens. Also, it feels like the car has a bit less power, which leads me to believe that one of the cylinders isnt firing. Anyone know what might have caused this?

 

Not likely, but it will be consistent as rpms go up.

 

I'd say change your oil and throw in some ZMAX or some schit like that before we start talking engine rebuilding

 

check the condition of each spark plug, check the resistance on each plug wire, check the condition of the distributor cap and rotor. these are the first steps in fixing a misfiring cylinder. when you check the plugs, look for cracks in the ceramic or just plain fouled plugs. check the resistance of each wire and make sure each plug wire is consistant with all the others. if you don't come up with anything, post back up here.

 

old and broken motor mounts will cause the car to vibrate heavily at idle, and more so if you're an automatic. running the a/c at the same time can contribute as well.

like the other guys said, check your plugs and replace if needed, how long have the plug wires been on the car? check the dist. cap and rotor and replace the fuel filter if it hasn't beenn done since you've had the car or don't know when it was last replaced.