usually an engine that bucks like someone turned the key on and off real quick is a misfire. Secondary ignition would be suspect. coil, wires,plugs... Putting the engine on a scope so you can view the firing pattern while it is missing would tell you what cylinders and the pattern could point you in the direction of what is the problem. Excessive KV could be an open in a spark plug
wire. A very low KV could be a shorted wire or low compression. The burn time could show you if the cylinder is not getting enough fuel.
you might want to try another scanner first. You should have had codes stored in the computer. The check engine light should have been flashing on and off while you were driving to say that you have a serious problem. It sounds like you have a misfire going on. Misfires will send raw fuel into the cat. That can overheat the cat and damage it. That's why the check engine flashes, to let you know the problem could damage the cat. The cat works by burning off the extra hydrocarbons that your engine missed in combustion. when you dump excessive fuel, like from a misfire, the cat will try to burn all that excess fuel and get super hot. It could even heat up your floor in the vehicle.
if your computer didn't have any codes, except for the map that you unplugged, you should use a different scanner. With a catalytic converter working that much you should have had codes and/or pending codes for something.
I would not drive it around with it running badly. Your cat might not be damaged yet but if you keep driving it might.
You could also have a bad coil driver in the computer but that should have a code also. Disconnecting the battery and clearing the codes will make if harder for the next person to try and figure out what is going on because you have erased the information that might have been stored in the computer.
Some scanners may seem to ask for manufacturer specifics like they have information from the dealer but then just look at generic OBD2 when scanning for codes. OBD2 generic is for emissions. Manufacturer specific will have a lot more information