Hey guys got a 05 cummins pretty well stock except for intake horn and smarty, i know i could use injectors but the truck randomly stopped getting the boost it used to, i have a tubed guage from the intake it used to climb to 28 lbs no problem but now it climbs right up to 20 lbs and flat lines, all connections appear to be good, cannot find or hear any leaks. Any input would be much appreciated. THANKS!

 

Check the intake horn pressure/temp sensor, you'll probably find it totally clogged. There is an updated one from Cummins available. I had problems with my boost pressure last year on my 2011 and replacing that sensor fixed it.