Jaws II (Sunday at 8 p.m. on...

Jaws II (Sunday at 8 p.m. on ABC) is an uneven sequel that never succeeds in being as scary as the original. It has a stronger, better developed relationship between Roy Scheider, police chief ot that shark-endangered New England resort community, and his wife, Lorraine Gary. Yet long before we reach a preposterously blazing finale, the film’s credibility has been eroded by a rising tide of hokum. This time the shark has a whole flotilla of youngsters, including the police chief’s own kids, as a target.

If Tomorrow Comes (CBS Sunday at 8 p.m., Monday & Tuesday at 9 p.m.) is a seven-hour miniseries based on the Sidney Sheldon best seller.

The Culpepper Cattle Company (Sunday at 6 p.m. on Channel 9) is a solid Western with a real feeling for time and place. Gary Grimes stars as a youth in search of his manhood who joins a cattle drive only to develop a revulsion at the folly of violence.

Tell Me a Riddle (Monday, Channel 50 at 8 p.m., Channel 28 at 9 p.m.) is a deeply felt film about old age and death that is also a celebration of life and love’s miraculous powers of renewal. This tender yet unblinking adaptation of the Tillie Olsen novella marked a terrific feature directorial debut in 1980 for actress Lee Grant and was a personal triumph for its stars Melvyn Douglas and Lila Kedrova. A remarkably affecting film.

First Blood, the involving but ultraviolent--and ultra-disturbing--introduction to Sylvester Stallone’s ex-Green Beret John Rambo, repeats Monday at 9 p.m. on NBC.

Posse (Channel 13 Tuesday at 8 p.m.) is a handsome, entertaining Western with a post-Watergate sensibility, produced and directed by Kirk Douglas. Douglas stars as a formidable Texas marshal running for the U.S. Senate but pursuing Bruce Dern, an elusive, cagey train robber who reveals Douglas for the unabashed political opportunist he is. Other Westerns in Channel 13’s 8 p.m. slot this week include Sam Peckinpah’s masterpiece manque Major Dundee (Wednesday) and a fine pair from Anthony Mann and James Stewart, Winchester ’73 (Thursday) and The Far Country (Friday).

Robert Conrad stars in the new TV movie Assassin (CBS Wednesday at 9 p.m.) as a secret agent in pursuit of a murderous humanoid robot.

True Confessions (Channel 5 Thursday at 8 p.m.) is an engrossing, richly detailed portrait of corruption and ethnicity starring Robert De Niro as an ambitious monsignor and Robert Duvall as his brother, a tough LAPD cop, whose lives are blighted by a Black Dahlia-like murder case.

Although The Jayne Mansfield Story (Channel 2 Thursday at 9 p.m.) glosses over the seamier aspects of its subject’s life, Loni Anderson shows us the increasingly grotesque public figure and the increasingly pathetic and boozy woman behind it.

The Oscar-nominated Las Madres de la Plaza de Mayo (Channel 28 Saturday at 4 p.m., to be completed the following week) is a heartbreaking but inspiring account of the mothers and grandmothers of Argentina who risked their own lives to protest the fate of their missing offspring who disappeared during the rule of the military junta.

The Great Scout and Cathouse Thursday (Channel 5 Saturday at 6 p.m.) is a 1976 comedy-Western with Lee Marvin and Robert Culp that isn’t nearly as funny as it thinks it is.

You don’t salute Private Benjamin (CBS Saturday at 9 p.m.), you court martial it. Goldie Hawn plays a rich, dumb girl who joins the Army where she sends shivers of rage through her superiors, played by Eileen Brennan and Robert Webber.