Ok - Here's my findings:
I have an '07 f350 fwd, purchased with 85,000 miles. Ran fine when test drove it but had a rough run issue when cold - not terrible but definitely noticeable - would smooth out as soon as the engine began to warm and would seem to run fine from then on.
Did some searching and it sounded like injector stiction so i ordered a bottle of HotShot Secret -- Hot Shot's Secret | Diesel Engine Oil Additive
Changed the oil and used Chevron DELO 15w40 and added the hotshot.
The rough running instantly got worse. Hotshots paperwork said this may happen and give it about 1,000 miles to work itself out.
I gave it 3,500 and no real change, rough running when cold and mileage took a dump also. Never had any smoking issues - black or white.
I also bought their Diesel Extreme fuel additive and used it -- no real difference noticed.
I also bought their Friction Reducer. Added this after about 3,000 miles and it made a noticeable difference but did not solve the problem either.
I pulled the EGR valve and cleaned it. it wasn't very dirty / sooty but it made an instant difference in starting. Truck started much quicker. ( it never took too long to start but it seemed like it should start faster than it was). It is possible it was sticking open and now is working correctly?
I then read about using a different viscosity oil and/or using REV-X. After adding the Friction reducer and getting some improvement, I assumed it was due to "thinning" the DELO 15w40 somewhat?
I changed both fuel filters and added the "blue spring" fuel pressure upgrade and still made no difference - so I assumed it was not a fueling issue.
I completely flushed the coolant - 6 times, using ford's coolant flush and their gold coolant. Coolant did not look too bad, no evidence of head gasket problems or "puking" and the oil temp and engine coolant temp are within 10 degrees of each other - So assumed it was not an oil cooler problem.
I'm convinced it is not an injector issue so I go to plan B....
I order two bottles of REV-X .. a total of 8oz. The HotShot bottle is 2 quarts!! Plus I added a quart of their friction reducer! I'm thinking that REV-X is an awfully small amount to treat 15 qts. of oil.
This time I use Shell's T-6 Rotella synthetic oil 5w40. I should have used this first and run the truck for a while -- and then included the REV-X to see if it worked without it but I went ahead and added it with the oil change.
WELL GLORY BE!!
She started instantly and ran perfect as soon as she started!!
I find it hard to believe that the REV-X would work that quickly and I attribute 90%+ of this success to using the right oil! After hearing all the testimonies about HOTShot's, I'm sure if there were a stiction issue to begin with, it has solved it - for me anyway. I'm sure the REV-X will do what it says but I should have waited to add it to give a fair assessment.
This made for a couple of expensive oil changes but still cheaper than an injector replacement.
FYI - I also added a Sinister Diesel coolant filter kit and an Amsoil bypass filter kit. Planning on keeping the truck for a while so trying to do whatever preventive maintenance I can.
If anyone has any questions about installing them - let me know.