My local Toyota dealer has the MAF for $110, part number 22204-75020. If you're paying $350 for labor to replace the MAF, you're getting ripped off.
Assuming they diagnosed it correctly as a MAF sensor issue, you could try cleaning it first.
Toyota 4Runner MAF mass air flow sensor cleaning - YouTube
If you have to replace it, watch this video (listen to the comments about not using power tools), it should be similar or the same setup for your engine:
HOW TO SERVICE A MASS AIR FLOW SENSOR - Toyota Tundra 4.7L V8 2000-2006 - YouTube