The xray you have attached is difficult to see, but I think I can see the dark area (radiolucency) on the side of the one root. This could be indicitive of residual infection.
Based on my recent research that I have come across, root canals seem to cause health problems for many people. Look into the research of Dr. Weston A Price.
Tooth decay as well as infection present in the mouth can produce a very foul odour. This may certainly be contributing substantially to your bad breath.