There are a few clues, depending on what you’re chasing. If it’s fuel trim codes, Freeze Frame data will give one clue. A contaminated MAF tends to over report at idle and under report under load.

On a naturally aspirated engine, MAF gm/sec will generally be a few tenths over the engine size in liters at hot idle. At 5000 RPM WOT it will be about 42 gm/sec per liter engine size assuming 85% volumetric efficiency.

As examples, a 5.3L will be about 5.6 gm/sec at idle, at least 222 gm/sec at 5000 RPM WOT.

Bear in mind anything that restricts engine breathing will reduce MAF readings under load (extremely dirty air filter, restricted exhaust, mechanical timing).