Josh, hope this doesn't run you around... . but... .
We have a IH with a CAT that uses and electronic throttle... its got to be close to 500K by now... we've had the same problem and a friend from CAT suggested we spray the throttle position sensor with contact cleaner and see what runs out... . we pulled it out and gave it a shot... . it looked like a creek running mud... and than worked fine...
I've not had a problem with my high mileage trucks... . all are now over 100K with one now over 300K... but after the fix on the CAT I'd pull it out of the truck and see if dirt/dust could be the cause... . I'm sure a bad connection at the pedal would set a code...