I had the rear motor mount changed because the old one leaked out the hydraulic fluid. Since then the car idles rough, especially when cold. The mech. took the new mount out and examined it and reinstalled it. The roughness was not as bad, but it is still there. The mechanic and I agree that this doesn't make sense, but it's a fact. Does anyone know what the cause would be?

 

the trans and tbelt mounts are the weight bearers