1998 Ford Taurus ( What is wrong?)?

1998 Ford Taurus Bad Catalytic Converter symptoms?
Bad Catelattic Converter in 1998 Ford Taurus??
Loss of power, Bogges down at hills, Little Rattle.
43 minutes ago - 4 days left to answer.
Additional Details
Manifold has been recently cleaned
Spark Plugs replaced
Fuel Pump Replaced
Fuel Filtler Replaced
Fuel system cleaner replaced
Air Filter replaced
Oil change already performed
My car boggs down it started it just last night. The exhaust has to be stopped up. I have had the car 3 years and I have put 25,000 miles on it, I bought it with 104,000 miles on it. There is no telling when the last time the exhaust or catalytic converter has been replaced before I bought it. Lets reaccess this please.

I was at a red light stopped, All of a sudden the RPM's got really low and wanted to shut off. So I ran the red light and tried to get to the apt as quickly as possibly before I got stranded in the rain in the dark. I flew up the hill and put my foot in it so it would go. Never had to do this before. I pulled in the parking lot turned off the car took a breath started the car back up. I revved it up two times. it seemed fine. So I took it up another nothc.. revvvvvvvvvvvvvvvvvvv reeeeeeeeeevv spit spit spit. Rotten Egg Smell and some rattling. I have replaced everything on this damn car! It is pissing me off. I am still making payments too. This anger isn't directed at anyone I am frustrated and I think I am going to loose it soon.

Took it to Pepboys they can't figure out what is wrong. Took it to a muffler shop had the catalytic conveter checked and exhaust checked nothing wrong there either. (NOW THEY TELL ME IT COULD BE A TANK OF BAD GAS!!!) I have been bent out of shape of this all weekend and they are going to tell me it is a bad tank of gas?