1995 Toyota 4Runner will not idle right and blows black sm

I was having problems with gas mileage so I changed the plugs and wires on my vehicle since I did this the idle on the vehicle is under 1 and wants to stall unless you have your foot on the gas it also has black smoke coming from the exhaust that smell like gas the vehicle did not act like this before I have checked the timing and it does not seem to be that. Could you give me some insight. I feel that it could be a vacume problem