Runs Rich!..Help Please

[Mits3kGT]

So my VR4 is running riiiiiich! I changed oil and about a week later its starting to smell like fuel again. I know its running rich due to these symptoms:

-when i rev (lets say to 4k) black smoke shoots from the exhaust
-when trying to drive a steady speed at anything over 3k rpm it hesistates and bogs down.
-i can be driving in 1st gear and stand on it, and it'll back fire and hesitate before taking off (only sometimes)
-oil smells a bit like fuel
-bad gas miliage

I'm not quite sure what can be causing this, i have confirmed and checked the following:

-MAF - i have started the car and unplugged it and can physically hear the car run worse with it unplugged. Plug it back in and it returns to a normal 'healthy' idle
-Pressure Testing - found a few leaks and proceeded to fix them yet the problem still persists.
-More Boost - thinking that with the excess fuel add more air to help lean it out, it still continues to run rich and blow black smoke even at 14psi.

I have no idea what can be causing it to run so rich? ECU? Maybe a bad O2 Sensor? Can anybody help me ask i hate wasting my dollers on gas when i know i can be getting better MPG and even worse, i hate putting the added stress on the motor. Will Rep anybody for helping out...Thanks

[PureN/AHP]

What boost are you running at now? Did you try dialing it back to stock boost to see what happens? I don't think this would be the issue, but worth a shot.

Bad O2 is always a possibility, do you have a volt meter to check to make sure it is cycling? What kind of gas mileage are you getting, I get about 350-400 miles from a tank of gas with 15s and 550cc injectors if I drive it like a regular car which is never so I only get like 250 miles per tank.

[Mits3kGT]

It doesn't matter how much boost i run, i've tried wastegate (my boost controller shut off), 10psi and all the way up to 14psi and it still leaves a trail of black smoke at WOT.

As for gas miliage idk i've never had a full tank in it but i get about 17mpg on the highway and maybe 14mpg in town (on wastegate pressure). I've just a full BPU car still with the stock 9b's.

[kelvinTurbo]

you haven't hit rich until you put a supra pump in your car, I have had serious backfire explosions and burnt rear bumper, in your case I would suspect the O2 sensor, which in our cars is a royal PITA to change, another thing I would look at is the gap of your plugs, you could be getting spark blow out or fouled plugs