My car shakes all the time

When I am waiting at a stoplight the rpm almost drops to zero. I'm wondering why that is? When I am at a stoplight, the car shakes rough for about two seconds and then the shaking stops. I feel like its some sort of electrical problem because even when I use the window switches or turn on the air, it triggers that rough shaking for about two seconds. When I am stopped the car steadily shakes, the steering wheel and the whole dashboard, but when I put the car on neutral it's as silent as a library. But there are sometimes when I turn the air on or use my window switch, there is heavier shaking on top of the steady shakes. I ran codes on my car and I got a random cylinder misfire code but I'm not sure if that is what is causing all this random shaking and how to fix it.