A couple of comments here that I have learned.
The Series II N/A engine using a plastic upper intake manifold (plenum) and due to heat in the engine, it causes the manifold to warp and crack allowing coolant in....which is bad!!!
It usually results in new heads and major engine work. The SC'd version however has a supercharger as its intake manifold....not plastic. Also the Series I 3800'* have aluminum intakes I believe. The cracking of the intake manifold is inevitable. It can be slowed with a 180T-stat.
As for the cam sensor (code 41) I have this problem too, the cam magnet is broken and in order to fix it, it requires major labour to pull the engine apart to get to the cam shaft. Usually, when a mechanic or a "pro" is in there, they will replace your timing chain. I have been quoted 4-5 hrs at $85 an hr/plus parts. Jrs3800 had the same cam magnet/cam sensor problem. But he had the resources to fix it outside of a shop. Some of us are not so lucky. I just live with the problem. It affects my performance tho...
I didn't think this was such a problem on newer (ie 95'* etc) only on the older 3800'*