OBD Doesn't Connect Check engine light flashes, Catalytic Converter red hot

ok this is the problem.. On my 97 Cavalier, i was driving then my exhaust sounded like it had holes in it but then stopped. Then about 3 hours later it did it again. I had a lost power and burned alot of gas. I looked under the car and my catalytic converter was smoking. So i hooked up the obd reader and it would come on but it would work in my other cars. I don't know could it be a ecm problem. Any suggestions?

plugged cat ?? oxygen sensor detecting a problem ....flashing light

Could be a plugged up cat,put a new one on and do not leave it off.The old cat is worth money,$100.00 from someone that buys them from shops.