2003 F350 6.0L in Minnesota
171,000 miles
5,100 since oil change 15W-30 at the shop

I was driving on the interstate (50 miles of driving) struggling to maintain 70-75 mph at 2,200RPMs. I would accelerate and RPMs would go up to 3,000 but no speed. Before I could pull off speed slowed to 50 before dying. Sat on the side of the road 30 minutes before I could get it started. Had to give it gas. No misfires just quietly started. Couldn't go over 30 mph.

Towed it to my destination 135 miles thank you AAA.

Volts on 7Pin FICM read fine.
Checked the fuel fulters. Air Filter. Tank for debris. Nothing.

My coolant resevoir was lose and I noticed a lot of coolant in the driverside front wheel well and down the left side of the undertruck. Reattached after checking FICM. Hope that was all it was cause I couldn't find any leaks.

I had Planned to have the oil changed before the return trip before this all happened

New to Diesel engines but I like a challenge. Where do I go next?

 

Cleaned the EGR Valve and now it starts a lot smoother. No difference in driving power.
Changed oil to 5W-4o Full Synthetic and Ford Oil Filter and Ford Cap.

Idles Great, Can Rev up to 3,000RPMs no problem when in Park or N.
Once I put it in gear I can't rev engine passed 2,000 RPMs and struggle to go 20 mph.

 

I doubt changing motor oil would improve much.
Given the reduction in performance, is the MIL (check engine) light coming on? If so, have you scanned, or had the ECU scanned for codes?

 

I have no CEL on but no scanning equipment. Just really trying to avoid overpaying a shop to do something I'm capable of doing myself. If I can just find the problem.