1990 sundance...

i just bought a 1990 plymought sundance for $150cdn.... the body and interior are in mint shape.... i had to replace the head because it was cracked... the car was running perfect other than the fact that it was a little hard on fuel and it took a couple of min. to get it to idle properly.... other than that it ran perfect.... then the battery died completely.... there was hardly enough juice in it to run the interior light let alone anything else.... so i replaced the battery and now it wont start..... it almost seems like it is gwetting way to much fuel.... i can smell raw gas from the exhaust... would it be the O2 cencor even if the car isnt running?..... any help wiould be very usefull