What is the best way to diagnose a bad mass air flow sensor? on 2005 Chevrolet Impala

I had the car running, hit it with a rubber mallet lightly, the car ran smoother, then I unplugged it and nothing changed. The car stalls and runs rough.

Asked by for the 2005 Chevrolet Impala
1 answer 2 comments
If the MAF was the problem, the car should run better with it unplugged, on a GM product. If you can bump it and the engine does better, it is a good sign that something is wrong with it or the connection to it.
Thanks. I replaced it and took care of the stall. Now it has a slight misfire, I diagnosed it to number 5 coil pack. I put a new coil pack on and now it runs horrible. Could it be a bad new part?
Check to make sure the wires are on correctly