03 expedition used to stall after driving for an

Sounds like your muffler and/or catalitic converter are plugged. maybe even the tailpipe.backed into any dirtbanks? now that the muffler is leaking the engine can exhale. look it over,check it out closely I think you'll find your problem.

your catalytic converter is probably plugged. have it checked at your local exhaust place. The extra pressure may have damaged the muffler and is letting the exhaust breathe better thus keeping it from stalling.

Sounds like there is some sort of exhaust system obstruction and the system has now rusted through or broken between the engine and said obstruction, or possibly just exploded from the pressure. I'd have a local muffler shop take a look at it and get the exhaust fixed. The stalling issue should not come back and the louod noise should go away. If you are proficient with cars or good with your hands then you may be able to replace the exhaust yourself.