Stalled and now won't start after using upper engine cleaner

[AussieAnth]

I bought and used a can of LiquiMoly Upper Engine Cleaner tonight while doing some maintenance on my 2012 TS118 Superb with 79,000kms. I separated the air intake hose after the MAF sensor, sprayed half the can in, let it sit for a couple of minutes, started it and let it run while i sprayed the rest of it in. It ran rough and blew white smoke as expected then idled smooth for a few minutes. Went to drive off and got about 1km from home and it stalled. It just won't spark and ignite by the sound of it. Mechanic came out and tried a few things and his best guess is the plugs have fouled from the cleaning. 

We tried to start it many times and it coughs but never starts.

I was going to remove and clean all plugs tomorrow.

Any suggestions?

[Hoverurb]

If you have the plugs out just fit a new set, cleaning modern plugs can be a waste of time.

[AussieAnth]

New plugs in and it started first try. Old plugs were black and coated. I guess the upper engine cleaner cleared out some crap as intended. Drove really well but no doubt the new plugs helped.