1996 Ford Mustang Car shaking.

Shakes or Wobbles problem
1996 Ford Mustang 6 cyl Automatic 177000 miles

I have a 1996 Ford Mustang coupe. My car started shaking/vibrating recently and I took it to advanced auto parts so they could put it on the computer and diagnose the possible problems. It came back with a list of things, so my father and I started knocking them off one by one. We've changed the spark plugs and wires, got a tune up, etc. We've found a misfire in the #2 plug/wire. Changed them, and still the car shakes. One of the diagnostic listings was the ignition coil. That is going to be my next action (to get that replaced.) Do you think that is the most likely problem? And about how much should labor on that run?