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All 4cyl engines have vibration issues, because they only fire every 180 degrees of crank rotation.
So they are usually setup with higher idles, 800rpm or so, 850 with automatics.
And any misfire at idle will really shake 4cyl engine
Check motor mounts first
Open the hood so you can see engine in the gap under the hood
Set emergency brake
Put in Drive and keep foot on the brake
Give it a little gas
Watch for engine to lift up
Repeat test in Reverse
look for engine to lift up
A loose or broken motor mount will allow engine to lift up in one direction.
Engine should move side to side a bit but not lift up
In Defrost mode the AC compressor will cycle on and off, or of course if AC is on compressor will be on and not cycle.
If it seems to be cycling too fast then it is probably low on coolant, so low pressure switch is turning off compressor until pressure comes back up and then compressor starts again.
Computer monitors if AC compressor is on or off, when on the computer will bump up the idle because compressor is a load on the engine.
So if compressor is cycling on and off then idle would be up and down with it