A Lawrence man ditched his girlfriend in a car wreck and knocked aside an elderly woman taking in her trash cans before he was stunned by a Taser as he tried to outrun cops he allegedly led on an interstate chase, police said.Chad R. Tombarello, 30, pleaded not guilty yesterday in Lawrence District Court to charges he led a high-speed police pursuit that started in Methuen shortly after noon Tuesday, continued into Salem, N.H., and ended in Haverhill after he’d driven several times into oncoming traffic and crashed into two cruisers in two states.