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Discussion Starter · #1 ·
I have a 2000 2.5L. I've noticed over the course of the last few months of owning it that when I run the engine for a while that I get significantly less power. Like when I drive home in the afternoon, i can get up to about 55-60 and that's flooring it in 4th (5th gear is about useless as speed gradually drops while in 5th gear) About a week ago, I was driving around 60mph and it started to sputter. It cleared up after about 3-4 mins and didnt happen again until 2 days ago.

Now anytime my engine reaches operating temperature, it sputters and backfires when I give it throttle. I can turn the engine off for about 15 mins and drive a little longer and it does it again. I have just recently had the plugs and wires changed. I've read through some of the threads and they say its either a TPS or an 02 sensor going bad, but leaning more towards one of the 02 sensors, due to it only happenning when its warm.

I just thought I was going crazy thinking that in the mornings I can get on the highway and run around 70mph fine up until 2 days ago, but in the afternoons in the west tx heat I can barely get her to 60.

I get no fault codes showing up when I press the odometer reset button turn on key and hold. I'm thinking of going to autozone today and having them run it for codes, but i get no check engine light.

Does this sound like an 02 sensor going bad?
 

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Yep that sounds like a bad upstream (nearest the engine) 02 sensor. The 02 sensors are not checked or referred to when the engine is cold but the upstream 02 sensor is used to set the air fuel mixture once the engine has warmed up enough.

Your 2.5L should only have two 02 sensors, I would replace the one closest to the engine, aka the 'upstream' sensor. Replace it with an NTK, do not go with a Bosch.
 

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Discussion Starter · #3 ·
I replaced both 02 sensors and it seemed fine for a day or so, but I wasn't driving very far. Yesterday on my way home it happened again! Is there anything else I should check?

Is it possibly a fuel pump? I wouldn't think so since she cranks up first time every time. And the fact that this only happens when the jeep gets warm just puzzles me. I'm going out of my mind here.
 

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That very well could be your catalytic converter starting to clog up then. Mine was doing the same thing but it finished clogging up so quickly that the engine lost all power & I had to pull off the freeway 85 miles from home. The engine would idle fine but that was it.

Any shop that installs catalytic converters can do a pressure test on your cat to see if it is starting to clog.
 

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Discussion Starter · #5 ·
I will have that checked. When i went to lunch just now the damn thing killed and now it barely turns over. that seems to be the best option is to check it
 

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Discussion Starter · #6 ·
Took the jeep to the shop yesterday and had to leave overnight. Catalytic Converter checks out ok. He said it barely moved the gauge. So now I'm pretty much at a loss at what it could be.
 
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