Missing Episode: Leisure Suit Larry 4: The Missing Floppies. Actually, Al Lowe declared after the third part that he'd never make LSL 4. He kept his promise, didn't make LSL 4 and continued with LSL 5.
According to the video game book, Porn & Pong: How Grand Theft Auto, Tomb Raider and other Sexy Games Changed Our Culture. When the Larry series was hot, there were talks about a Leisure Suit Larry film. Jim Carrey was offered a role for the film, but he later declined the role. Al Lowe mentions that the studios offered Carrey scripts for the film that didn't feel like the game. This YouTube user states that they should have done a cartoon of Larry in the 90's right after LSL Love for sail.
Before the subtitle of "Love for Sail" was chosen for LSL 7, many others were considered. Some of them were included in the game as titles of books in the library.