CM2250 no boost in top gears

[hct5]

I have been having issues with our 2012 KW W900. It was demandated a couple of years ago and has been running grear with no issues. we installed a new trubo around 5 months ago and had no issues till about one month ago. the truck will run great for say 8 hours and then in the top gears 12/13 the boost drops to 0. sometimes he can drop a gear and it kicks back in and everything works great. i found the CAC leaking so i replaced that and it still has the same issue. new air filters. no leaks in the charge air system. cleaned the imap sensor. new exhuast pressure sensor and i also cleaned those tubes out. no exhaust blockages. just not sure where to go from here.