discovered an AFPR!

While checking my PCV valve I had to remove a little red vacuum hose from the FPR. While taking it off, I noticed it had an adjustment screw right where the hose went. The FPR wasn't very shiny, so I had just assumed it was stock. Anyways, the car already had a fuel pressure gauge mounted on the fuel rail. It was previously set to 35 psi at idle (800 rpm) and I bumped it to 40, just to be safe. (I was having idle problems) I've never tuned a car before and have a few questions.

1. How can I tell if I have aftermarket injectors? They have yellow tops, is that factory?

2. Can I turn the adjustment screw with the vacuum line off but the car still running? That would be a lot easier.

3. What is a good fuel pressure to set my car to? What is stock?

4. Should the fuel pressure be the same at idle and WOT?

Thanks for all the help, and if anyone can link me to some FP tuning sites that would be great!!!

I set it with the engine running? So 40psi with the vacuum line off isn't the same as 40psi with the vacuum line on?

Okay, I set it to 39 psi with vacuum line off and engine running. With the vacuum line on, the gauge reads about 31psi at idle. Is this normal?

bump. anyone?

Hmm... It didn't make a difference if I had my finger on or off the vacuum line, it was still at 39psi. When I put the vacuum line back on and let the car idle, it stays at 31 psi. When I stab the throttle with the vacuum line on it jumps up to about 39 psi. So just to clarify... that's normal, right?