08 W900 Cummins isx sluggish, white smoke at idle.

I have a 08 kw 900 with the Cummins isx en#79300625 the engine light came on and it’s says fuel delivery pressure mechanic says it the anti drain back vaule replace it and it’s still running a little sluggish,puffs of white smoke but only at a idle truck is fine when going down the road

 

I change the fuel filters already

 

Hopefully that’s it any thing other than the fuel pump the transfer pump is working can hear when you turn the key over

 

So is the fuel pump and transfer pump different

 

It’s crazy because I can fill both tanks and the rough idle goes away for a bit

 

Ok I will