LS1 Running Too Rich
I've started to notice that the inside of my exhaust pipes and the arse-end of my car have become very sooty as of late...this, along with the noticable drop-off in fuel economy (at least 1 to 1.5mpg average) point to my LS1 running way too rich. I had suspected it before the transmission failure, but it is obviously much worse now... while it was in for the warranty problem, the dealership performed a fuel system maintenance (cleaning the fuel rails and changing at least one of the fuel filters as to partially recompensate me for their first-time screwup.
What is weird is that with the Accel Blue flat air filter (essentially a European K&N filter) and JHP/HSV MAF tube I added ~10-12k miles back, the car should be getting more air. I haven't popped off the airbox cover yet (I will shortly), but there's no way the filter is dirty enough to restrict airflow this soon. Even assuming that the EEPROM computer did not properly adjust to these new additions, shouldn't the car be running leaner? Can an intake leak somewhere cause weird airflow problems that actually restrict airflow?
So-- I'm looking for suggestions. Should I buy a programmer and lean it out myself (ka-ching), or drag it back to the dealership and tell them to recal the EEPROM since I suspect their fuel service knocked the mixture further out of whack?