I have an 89 iroc that used to get 14 to 18 miles to the gallon. It has a 350 w/ dynomax headers and flomaster exhaust. Not any emmisions on it whatsoever. After I did the exhaust it now only gets about 8 to 10 miles to the gallon. I timed it and it still gets crappy milege. It seams to be running really rich. And a watery substance is coming out of the tailpipe. Loss of power to. what sensor or what could be wrong to cuase this. Please help gas aint cheap and I must have performance!!!!