Cobra help

I took my car to get hte safety and emissions and It FAILED the emissions the guy said that it was probably because it was running too rich, however the car wasn't really running very good, at all in fact i'm surprised the technician could keep the car started the car ran good until I got it to the emissions place then it started to idle funny it smelled like it was running really rich and it sounded like it was firing on only half of the cylinders, I have no idea what is causing this, is it my carb, or my igintion system I thought I had a bad connection on my coil so I changed the coil and the car ran great then it started to run like crap then it started to run good again, so I looked at the cap and rotor and they were brand new I cleaned them a little and replaced them and the car started and ran good again and on the way home from the emissions place I could hardly drive it because it kept dying and it sounded like it was again only firing on half of the cylinders then halfway home it started to run great again I think that if I fix this problem it will pass inspection, does anyone have any idea what's wrong?

Check your spark coming out of each plug wire. If that seems ok I think you might have a stuck float bowl on your carb. Is your carb a motoorcraft/autolite or aftermarket?

Wow, you still have to pass emissions on a 76? That sucks!! How do the plugs look? Did the car just start acting funny or has it being going on for some time? Have you done a recent tune up?

The car seems to be running ok now I rebuilt and put smaller jets in the carb, for my altitude I think that the jets were too big, and I reset the timing and I think that did it, I am going to go get it re tested. The engine is pretty new it's a crate motor and everything that was on it was basically new I just hadn't run it that much but now it seems to be running good. Also when they did the emissions they put the rear wheels on a sort of dyno but the dyno was raised so it raised the rear of the car a lot so I think that caused the carb to flood, if that's the case then I need to take it to another shop that has a level dyno, that same thing happened to a friend of mine and when he took it to a place where they had a level dyno his car passed.