Hey guys. New to the forum. Looking for some help and advice. My fiance has a 06 tc with 246k on it. Every now and then, it'll stumble. Either idling or driving. No codes, no cel, nothing. Changed the fuel pump, new plugs, new coil packs, cleaned the maf sensor, cleaned the throttle body. I'm at a loss with this one. My question is, could it be the cats r starting to clog? Original cats btw. Any help or suggestions are highly appreciated

 

Have you done a compression test? With that engine milage that high I would do an engine compression test.

The pressure should be around 189 Psi, with a minimum pressure of 145 Psi, and the difference between cylinders should be no greater than 14 Psi.

This may help.
https://workshop-manuals.com/scion/t...ons/page_1230/

 

No I haven't done it yet. I have a compression tester but it's for diesel so I'll have to get a different one. I figured since it runs fine most of the time, doesn't burn any oil, no clutter and rattle, I thought compression would be at least pretty good