I have a 2004 suburban with unknown milage. Last recorded milage i found was in 2017 at 275000. I drive it about 40 minutes one way for work down the toll road at 70 ish and after about 20 minutes if i kick it down it won't rev past like 3000 with out almost dying. Seems like its running out of fuel until i let off and it clears up and the longer i dive the worse it gets i got off the toll road and couldn't rev past 2500 without it dying out. Then after a red-light it died in the road i stopped waited 10 seconds and it started and after i started it it ran like normal when i took off i could accelerate all the way through the rpms with only a slight stutter

 

Change the fuel filter first. '04 still had one. Classic symptoms of a filter loaded up with stuff.