2002 freightliner strait box w/ 215 cat 6 cyl ,turbo, 6- speed, truck starts very hard, just cranks and cranks , some times on rainy days it almost wont start at all, repair shop at penske replaced feul pump , filters , injector o-rings, but truck still has the same problem , they tell me there is noting more they can do cuz there are no codes stored in the computer, keep runing it till it dont start at all , then call us , truck seems not to have the power it should, and it has a weird smell at idle , like its running lean , not the normal deisel smell.,i can hear the normal turbo , wine but is it sick ,no white smoke ,

Optional Information:
2002 freightliner 215 cat

Already Tried:
new fuel pump ,filters ,inj o-rings advil , tylenol