so i've been trying to figure out y my car is only getting 16-18mpg....and today i was checking the Fuel Pressure Regulator. i heard someplace that if u just take the vac line off the FPR the idle should change. so i tryed and got nothing @ all. the motors idle to begin w/ isn't very smooth, it goes up and down about 200rpm just enough to notice the tach move a little up and down. i've checked for vac leaks everywhere and found none. i've scaned for codes and got none. i think its either the 02 or the FPR but i have yet to unplug the power for the 02 to check tho i'm hoping the 02 is still good being that it costs $150 for a new one. but yea how can i check to see if teh FPR is bad or not?

oh and when a friend was driving behind me he said that when i get the on gas i get a puff of black smoke out the exhaust ... and being that black smoke is running rich i figured something is causing to much fuel to get in there