THE LONG VERSION: Norman Obsorn returned from the dead. Flash Thompson became an alcoholic, perhaps partially due to the fact that he turned down Felicia Hardy. Betty Brant intervened. Flash remained an alcoholic, verbally abused his father, physically abused his father, got in a car crash, had a good talking to by his big sister, got onto A.A., got hired by Norman Osborn (funny story, really...at the time, he was controlling the Daily Bugle and New York's crime scenes, and Spider-Man was being targeted for physically assaulting him in a fit of rage following a charity ball) as his, er, 'person who follows him around while he runs the Daily Bugle', Betty hooked up with Flash, Norman acted like an idiot, Norman went crazy, Flash lost his job but was much better, Flash broke up with Betty after regaining his asshole streak, Peter quit being Spidey (again), and then in the middle of one story Mysterio's replacement (the original had committed suicide, thank you Magic Hand - sorry, Kevin Smith) somehow got his hands on a set of Virtual Reality suits and kidnapped everyone involved in Peter Parker's life - literally, Aunt May, MJ, Joe Robertson, and a bunch of others - and put them through a virtual world to discover which one was Spider-Man. Flash's humongous ego seized the plot and turned it into a 'perfect world' where Flash was the supreme superhero of Earth living in a New York whose Mayor was Norman Osborn, Gwen Stacy and MJ fought with Betty Brant over the rights to love him, he defeated Doom, Annihlus and Blastaar all at the same time while his best pal Spidey and the FF watched. Eventually, Peter - a crackpot conspiracy theorist crippled by the accident which should have given him his powers - snapped out of the VR and unmasked the fake Spider-Man as Mysterio, at Flash Thompson's wedding to MJ. The "Perfect World" VR melted away, Mysterio did a supervillain getaway, and Flash pretended he'd save everyone because Peter didn't dare reveal himself in front of everyone.
THE SHORT VERSION: Howard Mackie, Tom DeFalco & John Byrne were among the people running things at the time. A lot of plot threads just never went anywhere, or worse, never went anywhere good.