2005 Crescendo with CAT diesel performance issues

[RockinAB]

Hi all
Was just wondering if any of you have had any issues with studder or slow go. There are only 23k miles on it and it is serviced regularly. I have tried additives, cleaning the jets and new air filter. It doesn't do it all the time, but it is happening more and more... I need it to go when I push the accelerator. It used to go every time. Please help!