2002 Chevy Avalanche Engine Misfire

I had my avalanche check engine lite come on on the way to work, so on the way home I figured I would go by Auto Zone and check on the Engine lite, On the way home I felt a slight miss as I drove further It began to miss worse, when I got to auto zone. There code scanner said I had a Missfire, But wouldn't tell me which cylinder. So I changed plugs and NO change, So I checked the wires and the coils, They all check OK. Now the engine runs so bad, only 1, 3, 5, 7 cylinders are fireing correctly. #2, 4, 6, 8 Cylinders barely make a difference when I unplug the coils, It also smells like something electrical is burning under the hood. Do you think my computer is fryed? Please Help!