Two weeks ago car went in to get tierods replaced, inner and outer. Picked car up and was making awful knocking noise from top of engine. Took it back to garage they said it needed oil changed but it had only been 3000mi since previous one. They changed oil and knocking went away. However, now the car has no power when accelerating and will not shift gears(auto trans). Has trouble getting to 30mph. Took car to different garage and computer told them 3 plugs were misfiring. Changed plugs and wires new air filter, still has no power. What is happening? Nearest dealer is 60mi away!