1995 Nissan Altima smoked spark plugs

my nissan altima 95 was ok, but since i cross a water line on the road, began to fail, so much gas consuption and black smog on the exaust, so when i unplug the maf sensor the hesitation stops and leaves of smoking the black smog, i dont really know what can be, i check up the distributor, inside were a litte oil but i clean it with throtle cleaner, and i put it back, i change the spark plugs to and the car ran good for a while, after a few minutos began again to fail . can you help me . please.