Engine miss

When you replaced the plugs, did one cylinder plug look fouled, or have a build up on it?
Here is what I would do. Find out which cylinder is missing. This can be done by disconnecting each plug wire one at a time and placing one of your old plugs in that plug wire laying on the engine block. This will do two things. First it will tell u if that cylinder is the one missing because the car will not get worst. Secondly you will be able to see if that plug is firing. Do this to each cylinder until you find the one that is missing. If the plug is firing, I would suspect a bad fuel injector at that clyinder. If the plug is not firing, then track back and see where you are loosing fire for that cylinder.
On a side note, a compression check could ease your mind on the internal workings of the engine.