Heavy vibration at stop light

Hey guys, new around here. I've got a 2008 Fusion SE, 2.3 auto that has been shaking in gear at stop lights. It's gotten increasingly worse. I really need some help here.

So far I've swapped the engine, transmission, and torque strut mounts, to no avail. A few weeks ago I found a deteriorated valve cover gasket with oil leaking inside and submerging the spark plugs. I cleaned it out, replaced the plugs, replaced the gasket. I really thought that was it, but once again no luck. The vibration is only getting worse and no mechanics around seem to know either.