I noticed after a day of hard Canadian driving that my Bonneville wasn't running as usual. When reversing and then going to drive the car occasionally stalls out, also the idle seems to be erratic, and now the bright orange "check engine" light remains on. I've encountered this problem on other cars in my career and seems to me to be the camshaft sensor, what do you guys think?

First thing to do is to pull the trouble codes stored - at a minimum, jumper the ALDL and read the flashes.

Sounds more like a dirty IAC particularly if idle is cycling up and down in park.

Yes pull the codes. Its easy on these cars. Check tech info articles.