Right around 45 or so.

would less then that fuel pressure cause this problem? I'm going to get it scanned and see what codes come up this week, but any other information out there?

I don't believe it'* the problem. I'm still thinking it'* limp home mode because of the 4th gear problem.

I will be taking it to a GM dealer, if I say I think its in limp mode, will they know what im talking about or is there a technical term for it?

That is the term.

You know a badly plugged fuel filter would restrict fuel flow to a point of causing the motor to not rev very high either.

When is the last time you had yours replaced? Just to rule that out to....

There are various safety features built into the pcm to keep your engine from blowing.

P/N will not rev over 4K unless you are moving over 15mph.
3rd gear is possibly limited as well to a certain speed which would then kick in the fuel cut off (like park/neutral).

Oil Pressure: Won't effect the performance of the car because the PCM does not read or monitor the oil pressure.

4th gear: Technically it'* probably the 4th gear clutch hub that went bad. The splines are not hardened until the 2003 model year and the poor design strips out. I have a couple that I should take pictures of for reference.

OK I am going in tomorrow to get it scanned, and was thinking of having them put a fuel filter on it too, whats the price on that and labor time?

If the oil pressure is pegged, 99% you have a bad sensor and it is unrelated to your llimited RPM issue. The loss of 4th gear may actually be directly related to the issue, in that the transmission failure may put the car into "limp home" mode (like Dan suggested).

Get the car scanned for DTC'*.

The cost of a fuel filter really depends on the shop. A new filter is about $10, and it take about 30 mins to change a filter. Under $50 would be my guess. I charge $25.