I wasn't suggesting that you had a skipping belt, I was just illustrating that the motor can run with the cam a tooth off or worse. It could be that both cams are off the same amount. The compression would be even across all six cyl's. You need to pull the top cover and check the cam timing., if it's ok then:
Check your ignition components (cap,rotor,plugs, wires)
Check that all the injectors are spraying clean gasoline.
Can you isolate which cyl is missing?
How is the cat? It may be plugged.
