85 Subburban black plugs, filter

I have a 85 Suburban

I rebuilt the carb and ajusted the float. It is a 4brl carb

The filter gets some oil through the tube from the top cover of the engine, the plugs are always black with carbon
have to change the plugs every 3to4 days
the engine stalls once in a while like it is choking
Please help

Jumbo Canada