Camshaft and Crankshaft position sensor
 

I am curious if anyone can help me out, I have an 2003 Seville SLS and love the thing. It only had one owner and no accidents. It is high in mile but runs mint. The only issue that I am having is that it takes a lil bit to start all of a sudden and when I am at a stop it wants to cough a bit and there is a little drag once I hit the gas again. I did a diagnostic check with my onstar and am bringing back a possible camshaft position sensor or crankshaft position sensor. I understand there are 2 of each and would like to know where to locate the dag gone things so I can replace them until the issue is corrected. Can someone help me out there ??