There are all too many news stories of motor vehicles mounting curbs and striking pedestrians with tragic results. Two incidents like this occurred in Manhattan just this past Friday afternoon. But one of these incidents has an unusual element: according to witnesses, rather than an apparently random occurrence,the driver of the vehicle and his passenger were following the pedestrians just before mounting the sidewalk. At 5P.M., a 28-year-old pregnant woman, Ysemny Ramos, was killed while she was walking west along East 37th Street, between Fifth and Madison Avenues. According to the police, the driver, Keston Brown, was apparently intoxicated and following the woman and a co-worker, Tassia Katsiambanis, as they walked down the street. However, at an arraignment, Browns lawyer told the judge that the Gristedes van Brown was driving had a history of mechanical troubles. According to witnesses, the driver of the van pulled alongside the women and began slowly following them. A man in the passenger seat hung out the car window, as if looking for something or someone, one witness said. Police sources said he was shouting come-ons at the two women from his window before losing control of the delivery van. Katsiambanis said they never heard any comments or even noticed the van until it was on top of them. Moments later, the van jumped the curb and crashed into the women, pinning them to the ground. The van moved with such force that it toppled a parking meter, a signpost and a bollard meant to protect the parking meter. Tassia Katsiambanis, 37, of Queens, was listed in stable condition at Bellevue. The women worked at Israel Berger & Associates, an architectural consulting and inspection firm at 232 Madison Avenue and had just left work for the weekend before the accident. Mr. Brown was arrested at the scene and charged with driving while intoxicated. He had been a carpenter and maintenance worker for the Gristedes supermarket chain for at least two years, and was taking the van home for the weekend to respond to emergency calls, an employee said. After the accident, he got out of the van, looked at Ms. Ramoss body and promptly left the scene, according to a witness. He barely made it up the block before police officers grabbed him, several witnesses said. He was arrested on charges of felonious assault and driving while intoxicated. Fridays second accident occurred about an hour earlier when a group of people were injured when a taxi, apparently rammed from behind by a silver Hyundai, jumped onto a sidewalk near Amsterdam Avenue and 106th Street slamming into the window of Mamas Pizzeria. According to the police, seven people including the driver were injured. At least one person (not the driver) sustained very serious injuries in the accident.