Done and done Will definitely keep everyone posted, this has been a long running issue so I would like to provide any insight I can to help folks in the future who run into this problem.

 

So the post cat O2 sensor is really stuck in there. I sprayed it down with Liquid Wrench Penetrating Oil and tried two different O2 sensor sockets and can't break it loose. Did manage to round off the edges, so it is pipe wrench time now. If all else fails I will just cut it off and drill it out. The pre-cat O2 was much easier to remove!

 

That’s weird usually that O2 is the easy one well maybe you guys in the rust belt may have problems in Arizona no such thing as rust.

Maybe this is an indicator to the outcome.

It was O2 time Ta Da

 

Update: The truck wouldn't idle at all this past weekend when I was out of town. I was in a higher elevation area and it was colder, had to keep giving it gas to keep it running. Once it warmed up it was fine. When I got home I replaced the MAP sensor... big increase in performance! Haven't had any stumbles since. Haven't been able to get the post cat O2 out still. Completely rounded off and even a pipe wrench won't budge it! However, I do think I may have an exhaust leak and that is what is giving me the lean short term fuel trim readings. I haven't narrowed it down yet, the weather hasn't been very good for working on the Dak. But I think it is either a manifold bolt or possibly the flange connection, maybe a blown gasket. Will keep updated once I find out more!

 

I know what you are talking about just talked to my Brother he lives in Meridian Idaho he told me all about the weather in Idaho.


gnelson49 the best may be to have a shop torch out that section and put in a new O2 section if your CAT is old maybe its a good time to just get a new CAT the O2 section should come with it at same time (two birds with one stone as they say).

 

gnelson49 the best may be to have a shop torch out that section and put in a new O2 section if your CAT is old maybe its a good time to just get a new CAT the O2 section should come with it at same time (two birds with one stone as they say).[/QUOTE]

I was thinking about that too, looked up a few Magnaflows the other day, pretty reasonable cost. I want to see if I can stop this exhaust leak and see if the readings change on the O2 sensor, then that will probably be my next step.