Rough Idle, Rich Smell

My wife's car's engine has been missing for awhile, I replaced all of the coils which helped. The mechanic replaced the harmonic stabilizer to fix other issues. Now it smells rich and has a rough idle, it seems to still be missing. The plugs and wires are less then a year old so it should not be those. I do not have the tools to check the plugs for oil etc, but will get them if needed. I plan to run some fuel injector cleaner through it and see if that helps. Any other ideas as to what could be causing this? Also the fuel gauge has been off and the low fuel light blinking randomly. Along with this had been a check engine light, but after replacing the dead coil the light immediately shut off. I cannot read the code as the computer is the cross between obd 1 and 2 so no help there.