I have 98.5 just purchased it month ago first diesel. It has raptor fuel dog runs great once started. And starts up no problem after warm. But rough start when cold. Have fuel pressure guage I have to bump the ignition for fuel pressure to build. Im thinking when shut truck off im losing pressure. Stays constant 18 psi when running.

 

My 01 Does something like that. Once the heaters cycle off and I crank it over, she cranks just a bit longer and rattles like a SOB for a half a second and almost sounds like its not gonna run, then jumps up to 900rpms for like another half a second then idles fine after that. As far as fuel pressure, I have 0 until i turn the ignition on and the pump runs for a second and it jumps to 14, then slowly falls back to 0 before I crank it over. From what you wrote it just sounds a Cummins in the winter man.

 

Did you do the modifications or were they already done? I know some people delete the grid heater, which can also make for a bit harder starting.