Hello I have a 1999 f550 with a 7.3 out of a 2002. I'm having trouble starting it the first time of the day, cranks and cranks and finally starts but runs rough for about 10 seconds (while giving it throttle) then purrs like a kitten. I've changed the ICM,MAP,ICP,GPR,IPR, and CMP. I've dropped and cleaned out the tank replaced the fuel pump, rebuilt the fuel bowl and installed new fuel line grommets, 2 new batteries.

Another issue I was running it for about 5 minutes and noticed coolant seeping out of coolant reservoir tank, I start to open it coolant is still cool but a lot of pressure and "boom"shoots out coolant which smells slightly like diesel and a bunch of brownish mud looking substance. I am new here but will try to figure out how to add photos

 

Well diesels need compression oh lord do they need compression if you have oil in your coolant then I would say that you have a blown head gasket or a Crack in your block . You will have to take your heads of to see if it is a head gasket best case scenario. But if you keep driving it you will cause more damage then you can imagine. Find out right a way. I hate to say stop driving your truck cause i love mine but please do so

 

Not sure if it's oil or fuel but I do know it smells like diesel

 

That is oil in your coolant no doubt about it diesel fuel will not do that to your coolant. And if you smell your oil when you change it it smells like diesel fuel as well.