Isuzu service engine soon light..

hi guys Need some help. I have a Isuzu for 900 sites 220. The service engine soon light comes on and it goes into limp mode. I had it scanned and was told I had low fuel pressure. I changed the pump and it ran good for a few days and now it’s playing up again. When I got it scanned he said I had a low boost pressure as well. Anyone had this problem??