2000 Toyota Celica

Engine Mechanical problem
2000 Toyota Celica 4 cyl Front Wheel Drive Manual 3000 miles

I recently had the motor rebuilt. And 3 weeks after the work got done I got a MIL light that read Idle Control sensor and catalytic converter. Well I found a bypass for the catalytic converter just so I can pass emissions. Installed it and reset MIL. Now I got this code P0300 could that have something to do with it misfiring? And I have my idle control part would it help to install that maybe clear up the misfiring?
August 4, 2008.

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