01 Cummins 24V camshaft sensor

Okay guys I got a code for a camshaft position sensor and won't go away. When I start my truck it runs real rough for about 10 secs then my RPMs drop to zero and my idle levels out and it runs great, but no RPM gauge? And so a little back story, when I first bought the truck guy said it had a bad ecm, and was tuck in limp mode? So he gave me an extra ecm and a pcm and said he pulled them from a junk yard. So I slapped the new ecm he gave me in it and it drove fine. Minus the RPM gauge. So I took it in and got the ecm flashed. But now my problem is when I plug a nice fanny scanner in it, it tells shows me a different vin and says my truck is a 99? My truck is a 01. 1/01 to be exact. So long story short, my question is do you think the place I took it to didn't really flash it? Or if they did, did they not program new ecm to my vin?? And I replaced camshaft sensor twice! Which was a pain!!! So do you think some how some way the ecm is not registered the cam sensor?? Any help would be awesome. Thanks