1999 F-350 Crew Cab, Dullie, 4x4, V-10, Automatic.
New long Block 20000 miles ago, New coils 5000 miles ago, Fuel filter changed 2 years ago.

Runs rough on idel and when a demand is put on it, such as going up a hill or giving it gas during 1500 rpms. KIck it down and it goes pretty good, so I can say it's getting fuel. I ohm checked the injectors ave 15-15.1. Cleaned MAF.

Auto Zone said it has random 300 code, could be a number of things, nothing points to any one cylinder.

I put a strong fuel cleaner in a 1/2 a tank, drove it until it was empty, filled tank and drove it some more.

I still have the same rough idel, I do notice a strong sulfer smell from the exhaus. like the CAT. Never had the smell before.

What do you think is wrong and how to fix it.

 

Sulfur smell = bad cat.

Time for a new fuel filter, too.