The car failed the emissions test at the dealership due to high hydrocarbvons. Mechanic said he could try to correct by leaning out the mixture. He did.
Now the car stumbles on idle,takes several tries to start when cold and idles at about 400 rpm when cold and dies when placed in gear. After several iterations of this it finally goes.
What do I need to be armed with when I take it back to the dealership. What might the mechanic done wrong? How is the fuel mixture adjusted ? The car just had it's 60000 mile service about six months ago.
Your advice please.