Miami Vice question?!

Miami Vice question?

Does anyone know which season did Michael Mann leave the series and why was he still given executive producer credit, afterwards?

Not sure really when Mann left but here are a few reasons why the show ended:

The reason the show was cancelled was declining popularity and errors in managerial judgement. at the beginning of third season (1986–1987). The first reason for the shows demise was an ill-fated decision to move Miami Vice to the same time slot as CBS' Dallas, which was a popular show at the time.

The second reason was Michael Mann's decision to give the show a darker, grittier look, feel and touch — a definite change from the tone of the first two seasons, which involved darker, non-pastel wardrobes. Fans were miffed at the series' new look and began to turn away, which led to the reintroduction of pastels for the fourth season (1987–1988).

The third reason was the original writers for the series had left by the fourth season, and the episodes often followed all but ridiculous and/or boring storylines. The most infamous example was perhaps what is known among fans as the "alien episode" ("Missing Hours") — in which James Brown plays an alien leader. There was also a love affair between Sonny Crockett (Don Johnson) and Sheena Easton, which turned people away from the show.

Another reason may have been when Crockett gets amnesia (in which he mistakes himself for his drug dealer alter- ego, and becomes a hitman), though this ended after a short while. Also, Jan Hammer departed from the series at the end of the fourth season. Tim Truman was a worthy successor in his abilities to deliver proper score music in his own right, but to many fans, it meant a farewell to yet another idiosyncratic element of the show's style.

The fifth reason was Michael Mann being replaced by Dick Wolf as the series' executive producer, a decision that had more than a mere subtle impact. The fifth season (1988–1989) meant yet another change in color tones and attitude, with storylines once again becoming dark, fatalistic and gritty — enough so that even some of the most loyal fans were left scratching their heads.

The sixth reason was that around the end of Season 5, Don Johnson had less screen time because he devoted much of his time to investing in his acting career beyond "'Vice". As Dick Wolf recalls in an interview for E! True Hollywood Story, after the fifth season, it was all just sort of "over", and the show had simply "run its course".