2017 LT Rough idle, stalling, foul smelling exhaust
 

2.0L turbo.
This began overnight - no warning.
Starts every time. Runs rough for a few seconds then quits. Excessive grey smoke out the back with a sulpher smell.
Installed a new crankshaft sensor to start - nothing changed.
Here's the weird part, no trouble codes at all.
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Any solid advice would be great, thanks in advance. Mike

you may have a plugged cat.