Car sputters every once in awhile while driving as well as when stopped

My car is a ford escape V6 3.0 liter 2003

Every so often when i'm driving the car will do this sputtering motion(around 30-40 MPH) as well as when i'm stopped.

I recently replaced all the spark plugs and seals for many different things (valve cover gaskets, air intake, spark plug seals, air intake and exaust) to see if that would fix the problem (But nope didn't change) it still sputters. Any idea what it could be?

I replaced all of those things because the engine made a burning smell (oil) but thats a completely different question(unless someone can help… Like i said. Replaced all those things. Still makes burning smell. But i figure thats the residue. I've only driven it like 20 miles and still making burning smell. Do i just drive longer?)

Have you tried gas treatment?

Um