Big Problem! (maybe spark plug)

Ok I have a 91 passat 16v and I was driving on the freeway when i felt a slight loss of power. When I exited and came to the light, the car started shaking like crazy like it was choking. Once i put my foot on the gas it started to have this spitting sound that was very loud (sounded like a vw bug). I had no power, and could barely accelerate. I cant even think about going on the highway. Could one of my spark plug wires have gone out or has my spark plug completely popped out of the hole? Please tell me something good because I really dont want it to be my spark plug. That may suggest a whole new head =(.
Thanks!

If a plug blew out it would be very noticeable if you look under the hood with the engine running.

Yeah I tried that....but I said what the heck and took it to a mechanic. They replaced the spark plugs and it still shook. Looking mor into the problem, they found out that I was running on 2 cylinders. the other two gave out on me. SO, I have to get my engine rebuilt. =(

I Would Get A Second Opinion On It
I Had Problems Like That Before And There Is Few Other Things That Could Be Wrong

Yep! i got it checked out and it was a bigger problem than i expected. i cracked my head and so i need to replace it. Also some oil had somehow gotten onto 2 of my spark plugs. Anyway, I said the hell with it and got a complete rebuild of the engine. Luckily I know the manager of this place, because the real price of fixing this car isnt a joke!