Cat's run $60 to $120 each. O2 sensorshould be in the piping before the last convertor.

 

I went on advance auto website and check prices I seen they had some cat's that you can use one to replace the two and the O2 senesor was from $50-$90. hopefully I'll have time to fix the problem this weekend thanks for all your help

 

Good luck. Personally I always dread exhaust work (even though sometimes it's not so bad). The worst part is trying to find the right pipes in corresponding I.D. and O.D. sizes.

 

http://www.partsamerica.com/ProductD...45&PTSet=A

This is the catalytic convertor I purchased today from advance auto parts it is suppose to replace both of the convertors with this one unitfrom what I read. The guy that worked at advance didn't seem sure about a few things I asked him and said I needed two of them which I didn't understand since it cost twice as much as others. He said If I was wrong I can exchange it and buy a front and back. What do you think does this one replace both.

 

Well today I spent about 4 hours with my friend changing the catalytic and O2 sensor. When done started it up then went for the test drive van seemed much quieter and ran smoother but I continued to drive because I new it took a few minutes of driving before it started acting up.Just as I'm heading back It happens again now I'm lost everybody I asked said that the catalytic sound like my problem. Now I'm starting to think it has something to do with the transmission or torque convertor but like I said it drives fine when I first take off then after a few minutes of driven it feels like its losing power and I can only get up to like 35 mph but its like it is struggling to get up there. I just want to get thoughts of what you think it could be now. The motor gets louder and is shaking when this starts happing even when I put it in park.

 

funny thing, my new van has been doing the same thing, but because it has so much lifter noise and a little knock, i just figured the engine was crapping out.

i can't think of a many thingsmechanical that would make a broken-in engine run fine and then lose power when warm, besides some problem with valve clearances (but hydraulic lifters!). Could be something to do with the fuel injection sensors, a temp sensor could be malfunctioning, saying it's always cold leading to an over-rich condition ... possibly clogging cat's? now i'm completely guessing

 

Well the van is at the mechanics so hopefully he can figure it out and I'll get back to ya'll on what the problem was or is.