99 E-450 Intermittent Rough Running

[RLanghelm]

1999 Class C motorhome (E-450) 7.3 Powerstroke. Drove from Tacoma area to Reno (1 day) with engine running rough off-and-on. I would feel it getting worse at highway speed. Would pull over with rough idle. Shut-off and restart would resolve the issue. Get back on highway and it would repeat 100+ miles down the road. Then drove to Boise (1 day) with no problem at all. On the return trip to Tacoma my problem re-appeared about 200 miles into the drive. Again, I would pull over and restart, problem resolved for a bit. Sound like a cam sensor?

Thanks in advance, Ron