1993 5.7 350 vibration

when in gear and stopped the engine vibrates very badly. it doesnt do it in park, or neutral.

when i press the gas to go, all of this vibration stops with no sign of any vibration.

the car has 78k miles on it, adn i havent had it long. does anyone have any tips? will new spark plugs solve this?

Idle speed adjustment, vacuum leaks, worn or slipping transmission, all of these can cause these symptoms. So can low cylinder compression. Check condition of all hoses and see if that helps.

You have a bad trans mount.

You have a bad transmission mount.