Rapper POORSTACY is dead ... and it sounds like he may have taken his own life.

POORSTACY -- legal name Carlito Milfort -- died in Palm Beach, Florida ... according to the medical examiner.

The cause of death is unclear -- we're working on it -- but folks leaving comments on POORSTACY's most recent Instagram post are indicating they are under the belief he may have died by suicide.

POORSTACY was an up-and-coming artist from Palm Beach who blended different genres like emo rap, punk rock, and punk rap.

His biggest accomplishments had been a feature on the "Bill & Ted Face the Music" movie soundtrack, which earned a Grammy nomination ... plus a handful of collabs with Travis Barker .

POORSTACY and Travis actually worked together on three songs ... and the biggest one is called "

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