[Katshot]

Welcome aboard.
The problem you're having is most likely due to carbon deposits and/or a malfunctioning EGR system. Unfortunately, the catalytic converter could also be the culprit.
I'm not sure why you're trying to draw a connection between your antifreeze and carbon deposits but...........they actually have nothing to do with each other. A can of "Top Engine Cleaner" to remove carbon would probably do wonders.

 

[Katshot]

Don't forget that in order for you to get the "FULL" effect, you need to shut the engine down as soon as it ingests the fluid and let it "soak" for approx 10 min.
Just make sure you don't pour any type of fluid into an engine that IS NOT running and then try to start it. EXTREME MECHANICAL DAMAGE WILL OCCUR.

 

[Katshot]

Go to the GM dealer and ask for a can of "Top Engine Cleaner". I don't have the part number with me but I can get it. Directions are on the can.
The other products that you mentioned are shotgun type products that are actually fuel additives.