Have a problem with misfire. Took the car to O'reily's and ran diagnostics. Told code was for ramdom misfires. Changed plugs and wires, runs the same. Very difficult acceleration with a lot of noise and rattling, once running over 35-40, seems to run fine. Took back to O'Reily's, code again said ramdom misfire. Suggested coil pack. Changed one that appeared to have a bad stem on it, still the same problem. I'm lost. Service engine light solid when idling or accelerating, flashing when achieves 35-40 mph.