have a 03 cts and got the codes P0496 which is Evap purge valve, I changed it and decided to clean the throttle body with carberator spray, I used half the can after I put everything back together and went to crank the car it turned over and starting shacking violently and fell below 1000x rpm and the engine light was flashing

 

Did it clear up? The flashing SES light was because it was running so bad. You just need to spray the throttle plate and bore then wiper it off with paper towel.