I have a 1995 camaro lt1 383,58mm tb,30svo,255lph,11.3cr, Car has been running good i put new O2s in it 3 weeks ago now for the last 3 days the car loads up with fuel at idle, till the point where black smoke starts coming out and the car starts missing, it will only do it at idle in close loop, the o2s are reading about 250-280mv when idleing so it starts adding fuel but even with the fuel trims maxed it still read 250-280 with black smoke coming out the tail pipe, but soon as you hit the gas the o2 #s go up and it pulls fuel #s down and it runs fine, any ideas? it think the o2s took a crap!

 

Sounds like your O2 sensors are contaminated.