Mansoor Salahuddin broke into sobs at an official hearing yesterday as he recounted how his ailing wife "caught cold and died because they cut off my gas" in a dispute about an overdue bill.

Sallahuddin, an administrative worker for the District of Columbia school system and father of 14, said the cutoff at his far Northeast Washington home came near the end of February 1978. Just one day earlier, he said he made a $200 cash payment to the Washington Gas Light Co. on a bill that totaled$295.

At a hearing before the D.C. Public Service Commission on winter utility service cutoffs, Salahuddin said the gas company's workman spurned his plea to leave the service connected.

Salahuddin raid his wife, Ameenah, 45, who suffered from a blood disorder, caught cold in the unheated house and was taken to a hospital where she died March 4. Meantime, Salahuddin said, the gas service had been restored.

The cutoff came after Salahuddin's earlier check to the utility company bounced at the bank, he said, plaintively asking if there was anybody in the hearing room who never had a check returned for lack of funds.

Salahuddin said he was testifying because he had gotten only hostile responses from Washington Gas and no responses from letters he sent to the PSC and to President Carter. His main concern, he said, was why his monthly gas bill routinely exceeds $300.

Salahuddin, who said he lives in the old house in which he grew up, did not get an immediate answer, but was promised one soon. PSC Chairman Elizabeth Hayes Patterson told the PSC staff to investigate his case, and the inquiry began privately within minutes.

James W. Freeman, the gas company's consumer relations director, said his company also began its own review. "Once we have investigated, we may find that some of the allegations don't stand up," Freeman testified later in the day.

Elizabeth Noel, deputy peoples counsel, who represents the public interest before the PSC, said she was "concerned at the lack of attention," that Salahuddin had received. She said she learned of his case just two days ago. CAPTION: Picture, MANSOOR SALAHUDDIN... bill exceeds $300 monthly