MAF tables being out of whack in the chip can certainly throw the BLM table off and cause this, it takes quite a bit of work to dial them in. Once you change the intake and exhaust airflow on our cars like we all do it throws the stock settings off. So logging w/ something fast like DS and adjusting the tables is whats needed to bring the MAP back in line.
Any kind of vacuum leak is also a huge problem so check everything you can possibly check for that. Zip tie hose fittings and make sure all hoses are in good shape, put a new GM pcv in it make sure you have no exhaust leaks or cracks in the headers.
