Intermittent misfire on one bank

chevrolet
caprice

#1

Dear lovely community,
I have a 2007 chevy caprice v6 with LE0 engine 3.6L.
For a while now there was some sort of hesitation and was running rough on 1500 to 2000 rpms. If I floor it the engine will respond great. Now the car is running worse than before with random misfires on Cylinders 1, 3, and 5.
I have new spark plugs and the throttle body have been cleaned.
I don’t think it’s the coils because I have swapped the coils between banks and still have the misfires on the same side.
One thing I should mention is that I’m running catless at the moment until I can afford replacements. " yep, you guessed it, I’m a student "
However, even before that cats have failed, I did run into this infamous misfire.

Any help or points that could lead me to a fix, will be greatly appreciated.

Sincerely,
Stereotypical broke student from across the Atlantic


#2

You could have a vacuum leak on that cylinder head.

Yosemite