Probably to be best remembered for its steamy sex scenes between the physically fetching Rebecca De Mornay and the hunky Antonio Banderas (in otherwise oddly unappealing performances), "Never Talk to Strangers" certainly won't be remembered for its leaky plot, which finds a female psychologist refusing to come to terms with the possibility that her new boyfriend is stalking her. The film is rife with unexpected revelations and twists but the filmmakers' sly maneuvering, instead of sucking the audience deeper into this psychological thriller, are apt to make them feel manipulated. As the movie's plausibility sags, so too does its engagingness.    Starring Rebecca De Mornay and Antonio Banderas. Directed by Peter Hall. Written by Lewis Green and Jordan Rush. Produced by Andras Hamori, Jeffrey R. Neuman and Martin J. Wiley. A TriStar release. Thriller. Rated R for violence, language and some strong graphic sexuality. Running time: 102 min.