haus more than likely you have a boost leak.

if the car drives fine till some boost comes on, more than likely thats the culprit. with nissan MAF's it accounts for all air in the system....if under boost it starts leaking air out, then you'll start running real rich and it wont work right. my car had a STUBBORN boost leak on the turbo to hotpipe coupler.

if u cant track it down, and it runs fine in vacuum, drive it over to Z Fever and let them take a look at it.