well it started about 2 months ago its been sitting for a bit in my sig is a list of mods to help me track down the problem...well the check engine light came on i try to rev it up and at about 2000rpm is sputers like a vacume leak i have checked everyline and can't find one...checked the turbo to see if blades are screwed and still nothing wrong....i took a line off my BOV and put it back on and maybe coincidently the car ran fine after that ..to check if my bov is leaking i covered the vent and still won't idle past and no air coming out...so i left it for a bit cause the snow came now its thawing and i started it check engine light came on idled fine but the same problem with the eratic running past 2000 rpm and black smoke out the back now black smoke tells me there is to much fuel and not enought air... and then it started to surge rilly bad ..i went over everyhose , and wire that i could think of and i came to the throtle body and on the top left hand side "same side as the throtle pulley cable" is a black single wire going to a cylindrical switch and when i wigled it the idle leveled outso i disconected it but the check engine light is still on and still won't rev up any ideas on what sensor that wire went to and could that be my cause?