Help

Hey guys Im new to this forum and Nissans. I just purchased an 87 Sentra, E16s engine. The girl I got it from said it quit so she took it to mech who siad it needed new carb. When I tried to start it it seemed like it wouldnt fire until the key was let off start position and then it would fire. I messed around and got it running, but when I try to accelerate it would stall. I advanced the timming and it was better. Advanced it to theend of its slot and it runs great except every now and then under acceleration at first it studders and then off it goes. I dont think its carburetor because it runs so nice most of the time. Im thinking maybe timming jumped a tooth. Have any of you ever had this kind of experience and can any one ell me where the timming marks on the gears line up as I have no manual. Thanks in advance for any help.