1988 Running Rough, need advice

Hi all,
So, I have a 1988 4 door sedan, 305, all bone stock. Since this tuesday, I have been having a problem where the car is running really rough at low speeds, and it feels like it has lost power. When i switch on the A/C it seems to get worse, and when I am stopped at a light it will get really jerky. At higher speeds, it still is running rough, but feels smoother.
I drove the car about 150 miles this weekend, and it ran fine the whole time. On tuesday is when the rough running started. I am looking for advice on what it could be, and what to do to fix it. I am concerned that it may be bad gas, maybe a bad o2 sensor, or possible a carb related problem. Any advice would be greatly appriciated!

Captain Caprice

Check your:

Distributor cap
Rotor
Plug Wires
Plugs

Also check for:

Vacuum leaks