I got a log of a stock 2006 silverado 5.3 flex on regular pump gas. It is reporting 35.9% alcohol on pump gas. It has not had any e85 put in the tank. Several weeks after logging it is stalling and giving p0175. I believe it does have a cold air intake and also a aftermarket throttle body, i think a jet TB. Could the maf be oiled down or dirty? Possibly one of the parts skewing maf reading?