'Shahs of Sunset' New Cast Member -- A Hottie with Ex-Husband Issues

"Shahs of Sunset" producers are adding more sex and drama for the upcoming 4th season ... by hiring a new chick ... who's trying to remarry her ex-husband.

TMZ broke the story ... Lilly Ghalichi was 86'd from the show and now we've learned she's been replaced by Asifa Mirza -- a 32-year-old graduate school student living a pampered life courtesy of her retired ex-hubby, Bobby. As for the sex and drama -- Asifa and Bobby divorced after 14 months of marriage .... yet they're currently banging again. Who says you can't go back?

We're also told GG's gonna have a major storyline, too -- accusing Mike of trying to have sex with her in Turkey last year -- and even submitting to a lie detector test.