My car a 1990 Buick Century with 70,000 miles on it over the last few days has developed a rough idle when hot, and stopped at a red light the car fights not to stall....
When I drop the car into neutral or park the idle corrects itself and is barely noticeable...
The exhaust on my car seems erratic, and is making a put-put-put sound from the muffler...
A friend of mine did the paper clip trick to get the computer to spit out two stored codes... they were 12 (I know this means the computer is working) along with 15 and 48.... can anyone identify these codes and suggest what could be causing the muffer to make the put-put-put sound.... it almost sounds like muffled bubble wrap...