Can someone tell me what are the symptoms for a bad MAF sensor. This is on a 2001 Ford F-150 truck 5.4 engine.

 

Instead of us describing what the symptoms of a particular failure are, why don't you just tell us what problems you're having? Would save a lot of time and multiple threads going...

 

Some mornings when started up it misses and sounds like it is running on half the cylinders. After about 4 minutes of running, it clears up and runs fine. But today when after 20 minutes of running, while going up a hill or under load, it started to stall out. After a little while, I pulled off and turn off the engine. Restarted and the problem was gone. Tune up and the cylinder head temp sensor have already been ruled out.

 

Yes it could be a MAF, but your symptoms are also those of several other possible causes. A plugged fuel filter will cause fuel starvation, which can cause rough running. A weak fuel pump can cause intermittent rough running or even stalling, especially under load. Try cleaning the MAF with some MAF sensor cleaner from a local auto parts store and see if that doesn't help. If it helps, then you know it was the MAF. If it doesn't completely clear it, then the MAF needs to be replaced. If it doesn't help at all, then the problem may lie elsewhere.