Problem started theft system light on. Car would not crank. Did trick of getting of car, manually unlocking & then started fine. 1 wk. Later speedometer was going from 30, 80, 150, 40. Check engine soon light on. Check stability on. Trac on. Battery only 1 yr. Old. Replace battery on key fob. 1 yr. Old starter. My mechanic is at a loss. Please help.