1st off, the kenji p28 you have probably has a dohc 1.8L program on it that is running rich as hell like most of his programs do especially at the bottom end of the rpm span....

I recommend you resolve your Check Engine light issues by diagnosing them using a paper clip etc. The details are explained at http://phearable.net/tech under Troubleshooting

Once you resolve your codes & you still have problems, send the ecu to kenji & tell him what is going on. He will inspec the ecu & poissibly reprogram the rom chip for a 1.6L profile.

I have installed a kenji p28 into a friends 00 ebp. Only thing I did was tinker with his idle, besides that the car ran fine.

Good Luck.