The vacuum-operated engine mount is only used on automatic-tranny cars. Was yours originally an auto before the engine swap?

There may be some differences in the sensors for JDM engines. For example I thoughtthe VTEC oil pressure switch was just a USDM thing.

 

I think mechanic found the problem...
He replaced VTEC sensor and it works fine now, no CEL when I get on the hwy and also Idle speed is stable now.

Thanks so much for your help, all the best!