I Had my JDM H22A motor rebuilt and it idle's really rough? What are some of the main cause?

 

does the idle rise and fall continuously or does it just idle rough? if it is rising then falling your O2 sensor is probably bad but just replacing it wont fix it. (exhaust leaks will cause new one to go bad) if it is just idling rough then check for vacuum leaks or EGR system failure. does it run ok off idle?

 

dirty injectors
dead fuel pump
sticky thermostat