2005 Pontiac Grand Prix Will a tune up fix these issues?

Thanks in advance for the help.

A month ago the car started acting differently performance wise. It needed a boost from the gas pedal to turn on and it would shake when idling at stop lights. A week ago, on the way home from a long trip, it got even worse - to the point that I had to put it in neutral at every light just to keep it from shaking. It'd also squeal off the line. The engine light started blinking so I had my buddy check the codes and it came up as a bad coil group. He found out that it was the 1/4 coil group, so he replaced it for me. For two days the car was running perfectly again. Then all of the sudden the check engine light came back on and it started doing the minor shaking again, etc.

So, I brought it to Autozone and had the codes read again and here's what the print up says:

1. Cylinder misfire detected-cylinder number 1
2. Catalyst efficiency low-bank 1

The associate stated that a tune up would fix this issue. Is it really that simple? Thanks again.

-Mike