05 has erratic rail pressure at idel

[Gibson]

05 LLY with edge evolution CTS, cold air and no muffler. All stock fuel system. Rail psi at idel fluxuates from 3,500/4,000-6,500/7,000 after it's been driven for a few minutes. Milage seems alright at 17-18mpg and any rpm besides idel it doesnt skip a beat Anything I should check first? I'm not very familiar with duramaxes.

 

[Gibson]

The fluxuation is about every 5-8 seconds

 

[phale]

I assume those pressures are at idle, if so it sounds like the fca is sticking/jumping. Does the truck surge when it does this?

 

[phale]

I just reread and caught where you said it was at idle. It is a pretty sure bet the fca is sticking.

 

[Gibson]

Yes it's at idel. I'll swap one out off another LLY and see what it does.