My Maxima has been acting up recently with a rough idle, decreased mileage, sluggish acceleration

While stopped at a light or stop sign, as soon as I release the brake, my car just takes off without me pressing the gas pedal. Now when I say take off, nothing like going 35 uncontrollably, it gets up to about 1500 rpm and just feels like it wants to go. The rough idle is intermittent and the sluggish is all the time, there is also kind of like a ringing sound when I press the accelerator, seems to be coming from the passenger side, as in a pulley maybe? I have not replaced anything, but have cleaned the MAF, switched to full synthetic and use premium gasoline. Any help would be greatly appreciated for I am stumped.