Today i was driving and sudenly the engine started to run really rough, and it only feels when i stop, when i drive it feels normal what the hell?? can it be chain tensioners problem? or??

 

The engine starts perfectly and on parking is working more or less ok ( still not like it used to) bun when i switch to D or R position the car start to shake, and the sound from the exaust !!! it sounds like i have a hudge subwoofer in my trunk i can actualy feel the sound with my body
whell what makes me hapy is that the engine is not dead, works and sounds like sh** but still i aint gonna have to throw the car away...... i hope