I have a 1999 dodge ram 2500 with 120,000 miles on it. I've been having a problem lately with it stalling after it warms up. It stalls and hesitates and I have to give it a lot of gas just to keep it running. If i use premium gas or use an octane booster it seems to get a little better for a short time. When idling, if I give it gas and let of the gas pedal, i can hear a rattling noise coming from seems to be the area of the catalytic converter. I also have a check engine light on that I had checked at autozone. They said I have a bad oxygen sensor. I have changed the spark plugs and also installed new plug wires. Thanks for your help.

 

Have a muffler shop flow check the cat or use a infared temp gauge to test operating temp change (instructions can be found with search button)...If cat is good ,which I doubt, then change the sensors...The code usually says which one is bad too.

 

And if the cat is bad, here is the most likely reason.http://dodgeram.info/tsb/2000/09-05-00.htm

Check it and fix it, or you'll ruin the new cat too.

 

find out the actual CEL code that your truck has. not just autozone's diagnosis of the problem. they have a tendency to interpret everything into a 'you need a new $70 o2 sensor'. post the code back here and look it up on this site or google search.

if it runs ok cold and then seems too rich or lean when warm, it may be a bad o2 sensor. they're supposed to be changed every 60 or 75 or 100k miles.

 

Thanks for all your help. I think I can handle putting in a new cat. converter and 02 sensor, but the replacing the plenum gasket and all the testing procedures is over my head. How much should I expect to pay at a repair shop? If I only put in a new cat converter and o2 sensor, how long b4 they went bad and would I be doing any damage to the engine. I only drive this truck about 1500-2000 miles a year and only drive it once a week. Also, where should I get the cat. converter and o2 sensor, is ebay a good place? Thanks again.