Q: Car pulling when I change gears.

All the air that goes into the cars engine is metered. If there is unmetered air coming in somewhere it will be detected by the Oxygen sensors and a lean code will be set. A lean condition will cause a drivability issue if it is severe enough, sometimes to the point of keeping the car from starting. Lean conditions are usually vacuum leaks. Something like a loose or torn air intake hose can trigger a lean condition code. A torn vacuum line or leaking intake gaskets can cause the lean condition also. A mechanic should be able to determine where the leak is and repair it. The code stored in your cars computer is very important and can help pin point the leak faster, so don’t erase it.