Mark, thanks for the input. It was late when I wrote this but, yes 4 speed means only four gears. I will check for obstructions but, I did just change the filter which was overdue.The air filter service gauge shows okay but maybe upstream blockage I'll check. The only other issue is an oil leak near or under the turbo stand area.
my 6.9 had a screen at the intake. Do you know if there are any on the 7.3. I will purchase a manual today. Thanks again