I just bought an 04 expedition from a used car dealer. Of course it wasnt gonna be perfect. I replaced an O2 sensor and the upstream dpfe hose thinking that is what was causing the stalling but it is still stalling so far only while idling and there is a rattling noise coming from my exhaust under the passenger side as if there is a housing loose but nothing is loose. Do these problems coincide with one another? What is possibly causing the stalling?

 

The stalling could be a dirty AIC valve and the rattling could be a broken honeycomb inside the catalytic converter.