[BR3W CITY]

Check fuel pressure under some load as well, and see if it drops. When demand rises, the pump should be keeping up. If the pressured drops, then you might have a restriction, bad reg, or issue with the pump.

And as always, check for vacuum and exhaust leaks on any new swap. The ECM can account for a pretty decent leak on either side at idle, but under load from the trans sometimes they will bog. If your not running a full exhaust, then be aware that the o2's might be seeing clean air and throwing your trims way off without triggering codes.

Is this a stock engine, or is there motor work involved. If its cammed, you might need your tuner to bump up the load correction on the idle.