[Z U L8R]

your fuel pressure is not making you run rich, check your timing see if it's retarded, other than that the ecu controls the a/f ratio via different references from different sensors

such as, maf, coolant temp sensor, o2 sensor.

for the record, i've never used an aftermarket fuel pressure regulator. i don't see the point. you either flood your motor from idle to redline, or you starve your motor from idle to redline. why not just tune the air/fuel ratios and adjust timing through out your power band with a piggy back or a stand alone system...
gl,
Dave =]