(I might be stupid.) 2007 Chevy suburban LTZ with a 5.3

I was chasing a evap leak and used a smoke tester through the break booster line. Now my car is in limp mode good spark,all my lifters move, great compression sitting at a quick build up of 210. I have a stable track light,flashing check engine light with a p0300 everything is back the way it is…why would it be freaking out? My spark plugs are a little fould but not by much