Audi Coupe Quattro For Sale What Could Be Causing Idle Shaking On A 1990 Audi Coupe Quatro?

What could be causing idle shaking on a 1990 Audi Coupe Quatro? - audi coupe quattro for sale

Hey guys, I have an Audi Coupe Quattro 1990 and shaking at idle. I replaced the left front engine mount, and it seemed that it vibrates, but it was after the engine was still trembling. (The engine itself is actually a bit under the hood to tremble) What can you be?