83 lesabre dead cylinder HELP!!!!

I have an 83 lesabre limited with a 307
my problem is that i replaced the alternator today and also replaced the spark plugs after i installed the alt i started the car and it ran fine then i went about replacing the plugs. lo and behold after the plugs were changed the car started misfiring.I pulled each plug one by one while it was running and the only one that did not make the engine bog down was the #4 plug.
So i took the plug out and it was clean as can be however it was still getting spark, switched the wire then switched to the old plug and still the cylinder will not fire. I am positive it is the #4 cylinder but it has spark and fuel plus all the other cylinders fire what could this be?????
please help a mechanical novice.

Try replacing the spark plug wire. You may have broken it when pulling it off when the plugs were changed.

I would also check for a vacuum hose being broke.