I was wondering if I could disconnect the cold start injector (5th injector). If I just unplug the wire to the injector will this cause any problems? Will there still be fuel sent to that injector and will that be a problem.

You don't really need to pull the electrical connection but it won't hurt.

While trying to diagnose my rich idling car, I too pulled the cold start valve. I left it plugged in, but I pulled the fuel line off of the fuel manifold. In its place I installed a fuel pressure gauge. If you only pull the electrical connection and your injector is leaking, you'll continue to get fuel from there, hence why you want to pull the fuel line also.

I'm still idling rich, but it's getting better bit by bit...

You can, but it won't make any difference unless there's something wrong with the CS circuit. The CSV operates ONLY when the temps are down in the 30s and the starter is engaged. The first clue to the problem is the term "new cam". What "new cam"? If it ain't stock, you're looking at rich running problems. The Cap'n