[jblackburn]

Seafoam is great stuff -I would definitely recommend it at the interval that you ran it through.

So is this sea foam something that you can just put in the gas tank and let it run through and do its thing or what steps do you have to follow??

Generally, the instructions tell you put put 1/3 a can in the intake (to clean the top of the engine), 1/3 in the oil to clean crud from the oil passages, and 1/3 in the fuel tank near empty to clean injectors. I used it several times on my old car, and it always seemed to run much more smoothly and stronger afterwards. There was always a LOT of smoke too

Not a Cruze, but...

 

[jblackburn]

Same, never fouled plugs.

Still though, to avoid the risk of it, get a can before you change the plugs, THEN toss in the new ones.