just recently picked up a 04 G35 sedan. Cars been thru a few quite a few owners since it was “built”.

it’s been tuned on UpRev but I have no clue who tuned it. I’ve tried contacting the previous owners with no luck
car has codes for
P0058
P0447
P0300
P0138
P0037
P0057

Car ran great for a few days then started to misfire at a constant throttle when it would rev to 3k. If you kept driving it would get worse and worse and start to sputter. Car also black smokes a little.

it also try’s to die(sometimes will die) when you put the clutch in and let it idle down after cruising. I’ve sprayed the intake and all surrounding hoses for leaks aswell

went and changed the plugs and every plug was black on the tip from fuel(also every single plug smells of raw fuel)

new plugs made the car run great for 1 day then it started to do the same exact thing where it would sputter and get worse as you’d drive.

Was wanting some input/ recommendations for tuners