Car running really rich, can i lean it out myself?

[supermaxx123]

To make a long story short, I got the car back from the mechanic. It took a while to get it back. Too frustrated with the mechanic at this point to ask for anything else.
Car runs really rich. Starts up just fine and idle is kinda off, it bounces a little but the car is driveable.

My question is, can I personally change the fuel tables?
I'm new to this but am not looking for more power, just looking to just take my idle out of full rich.
I have the older style s300 installed not sure what exact model, also have smanager on my laptop.

What do I need to start making changes? I did plug in laptop to car and hit datalog and saw some info but I am still lost, not sure where to go from there.

Notes: Idle runs better when i cause a vacuum leak, by disconnecting boost guage(believe it or not, the mechanic delivered the car to me this way, when i plug hose in idle goes unstable)
Car is turbo and runs rich through the whole rpm range, my A/F meter stays at 10 or very close to it. Even out of boost which I do not go into seeing as it needs a proper tune.
I did fix a leak before the wideband sensor and also fixed small leaks before the turbo.
This is all AFTER THE CAR WAS RETURNED TO ME.

Thanks

[Spunkster]

If you are unsure of how to tune this I would highly recommend you find a tuner than can help you tune this properly or you could damage your engine.