dt466e engine code 333 repair imfo.

yes i have a 2000 4700 4x2 box van the check engine light comes and it acts like a derate the code that i get is 333/131 thru. 135 it acts like the 333 is the first one to come back how would i go about finding out what is wrong the truck has been at international dealer three or four times and they can't find out what is wrong they said APS/IVS/IRP/ICP or the HEUI pump the owner dosen't have or want to spend money on parts changing the truck dose this when it is under a load or pulling a hill turn the key off and then back on and it minght run wright the rest of the trip or for ten mins. and you have to cycle the key switch agin it appears to be getting worse any help or thoughts would be helpfull as i have 14 years with cat dealer as a marine and EPG mech./elect. had experience with cummins and 60 series detroit amoung other engines left cat and started my own shop about 4 years ago we also run three of these trucks the other two have air brakes and one is mechanical no problems with this one should have kept the other two mechanicals. thank you john britain