Detroit 60 series 14L hard start

Hi everyone,

I have a 2005 Freightliner Columbia with a 14L d60 engine. My problem is that it takes a really long crank every morning before it finally fires up. Sounds like it is loosing prime overnight so I replaced the check valve at the back of the head. Also while replacing I noticed that the fuel pump had very low pressure on the outlet side (line going to injectors). So I replaced the pump too. Now in the mornings it starts right up sometimes but takes really long sometimes. So now it's intermittent. Any ideas what it could be? I was also told that it could be TRS and SRS sensors. But if those were bad wouldn't it take long to start every time?? Mine only takes long during the first start after sitting through the night after its started I could turn it off and it will start right up everytime until it sits through the night again.

Thanks!