Vehicle recently started stalling when coming to a stop. The problem seems to be intermittent, but when it doesn't stall, the rpms drop to 500 and jump back up to 800. No problem in park or neutral. Getting p0401 CEL code, and catalytic converter is occasionally rattling real loud.
Replaced the EGR valve, dpfe sensor, TCC solenoid, and iac valve. Nothing worked. I ran a diagnostic using autotap, and the downstream O2 sensor read 0.
Could a bad catalytic converter cause the intermittent stalling?

 

A cat is more likely to be a problem under load because of the higher volume of exhaust that would need to pass through it. My first though would've been the IAC valve, but since you've changed it already I'd say you're having issues with the torque converter.

 

Will it keep running if you keep light preasure on the gas? If it does, I would say that more than likely your idle air control valve (IAC) is sticking.

 

I'd say check all your emmision hoses for cracks.

 

Well, I think I may have fixed it. Thanks everyone for the suggestions.

Here is what I did (hopefully it will help someone).

First off, I should've gone through the proper diagnostic steps before swapping out parts. I bought a vacuum gauge and removed the erg vacuum line. With the vehicle running, attach the gauge and apply vacuum. The vehicle should stall or run rough. My idle did not change. That tells you that you have a blockage. I removed the throttle body and could not believe how bad the EGR ports were blocked. There was about 3/4 of an inch of rock hard carbon sticking out of the ports. I took a metal pick and physically removed the carbon. I followed up with a whole can of tb cleaner. Put everything back together, cleared the codes and she ran fine. Still getting the cat code but I knew it needed to be replaced. I guess that will consume my next free weekend.