There is one episode I remember from airing on FOX that I have yet to see in syndication.

I can't remember the full plot, but Al and Peggy went to stay at a hotel or cabin in an episode.

This was from early in the show, before it got all "cartoony", but I remember something about Al and Peg "doing it" during the national anthem before televised football games.

Is this episode on syndication and I just haven't seen it? or is it not being included?

Well, I've only got vague memories of the episode you're talking about, but I think it WAS shown in syndication. One episode that's not only AWOL from syndication, but never even aired was a 1989(?) episode called "I'll See You In Court," in which The Bundy's & Rhodes' take some sleasy motel proprietor to court for videotaping the sexual trysts of their customers, one of which was a tape of Peg & Al sold to Steve & Marcie!