Could be may things, excessive cylinder wall clearance(worn engine), I would start with a tune-up.
An engine that vibrates at 3000 RPM has an issue with balance. The harmonic balancer or the crankshaft can become out of alignment.
The engine may be in need of a tune up.
The reason why it is vibrating is cause of the Engine Mounts. You have to get the Engine Mounting changed ! cheers.
For an airplane it vibrates a lot and it needs a super- or turbocharger at high altitudes
Things vibrate for many reasons such as a car engine when it's broken.
Excessive engine vibration can because by and engine that needs to be tuned up. The vibration can also because by worn out motor mounts.
It is probably missing. Have it tuned up and a compression test run on the engine.
If it only vibrates at idle in gear it more than likely has a severe vacuum leak. Can also be a broken engine or transmission mount.
hard starting in the morning. It could also mean hard starting when the engine is warm. If the sensor is bad, and the car is warm, it could be telling the computer the engine is cold, therfore making the warm engine hard to start because it will be telling the computer to add more fuel and the engine doesn't need it.
With engine cold (prior to first starting in the morning) and parked on level ground - remove dipstick and check oil level as shown
check the glow plug, if it is diesel
The sound of a jet engine vibrates more than the sound of a lawn mower.