Lately my car has been running pretty darn rich. When you shut it off and get out you can get a faint gas smell, and my friends are telling me that when I drive off at WOT, there is a little black smoke out the pipes. Engine has 173k miles, new iac, new collar nut, IC tube gaskets. Anything I should look at to check this? Also, is there any way to check if the knock sensor is pulling timing? Im suspecting it is because my motor mounts are fairly shot, and I've heard the vibration can be picked up as knock. Another thing, whenever I turn my car off hot, and try to start it again, it will idle really rough and erratically with vaccuum anywhere from 12-8mm/hg. What should I be looking at?