Question

2002 Toyota Camry, car idles hard when air condition is running. I got the engine code P0302

Answer 1

If you have a code P0302 that means the #2 cylinder is misfiring. This can be due to a bad plug or plug wire, possible issue with a fuel injector. When you turn the a/c on, it takes more power from the engine, so the misfire is probably more noticable.