Could be,in need of a tune up,
a vacuum leak,
contaminated fuel (water),
If we knew what year, make, model and engine more info would be available.
A worn or loose out of adjustment drive belt could be the cause.
when running acand adling tuck vibration bad
Ankle injuries from running my be caused by improper footwear, running on uneven surfaces, or bad running form. Using ice and anti-inflammatory medicine will help ease your symptoms afterward.
A car that is stopped with the engine running.
Taking your foot off the accelerator.
The earth's tilt causes an uneven heating of the earth. The uneven heating due to the tilt causes the different seasons throughout the year.
Usually a suspension or front end proble causes uneven wear on the tires and you get noise from them, similar to running on snow tires
There are many reasons why your car might vibrate while it is idling. It could be running too hard for example.
Yes, "sparkling plugs" is definitely detrimental to idling or smooth running of an engine
Idling is what your car is doing when it is just sitting somewhere running. As soon as you press on the gas it is no longer idling. Your idle speed is the number of RPMs your engine runs at when you are idling.
the uneven heating of the earth
Glass