I rarely trust dealerships and mechanics, all from personal experience. I think the worst case was when I had a bad starter, and the mechanic told me that the crankshaft was moving back and forth! Funny, the engine only had 2500 miles on it and the reason he gave still doesn't make sense to anybody.
Now, that being said, a bad MAF sensor will give you a trouble code. But those things rarely FAIL, most often it's just corroded or broken wires and connectors. And there was a manufacturing issue with them that does cause rough running at times, but doesn't warrant replacement (which usually gets you a part with the SAME problem in it).
But before I recommend a new sensor, what are the symptoms you are having? And what year truck?
My oil line fix
My 100k stopped odometer fix
Brace for impact, I'm in a "modifying mood". Massive thread count inbound.