Pontiac Repair: 1995 Pontiac Transport, fuel pressure regulator, pontiac transport

Question
I have a 1995 Transport with a 3.8L engine. It had 150K on it when I bought it and now has 180K.  Starts good and runs good for the mnost part, but it as this nagging litttle pronlem where sometimes it will stumble and even die at a stop light. It has always had this problem but it has gotten worse lately. I took it to a non dealership mechanic and had the plugs and wires changed, then I took it back and they replaced the knock sensor which did help with driveabilty but did nt fix the problem. I checked the fuel pump pressure and it was 34 lbs. My book says it should be 40-47 lbs. The mechanic checked it also and agreed that it is a little low but not so low as to cause trouble. I didagree. I think that the fuel pressure has to be in spec. I am getting ready to replace the fuel pump.  What do you think?
Thank you.

Answer
Hi charlie:

I don't have web access to spec's on cars older than 1998 but the 40-44 psi seems right to me 47 is a bit to high and 34 is way too low. are you sure your gauge is working properly? that low pressure shouldn't cause a stall at idle. It will lack power on acceleration and turn on the service engine light eventually. If your sure your gauge is right then try this pull the vacuum hose off the fuel pressure regulator the prerssure should go up by say 4 or 5 psi. if it does the pump can build more pressure. the next thing I would try is get a pressure cut off hose and install it in between the regulator and back to the tank. and partailly block that line off to see if the pump can build more pressure tha n it did with the hose off the regulator. Basically what you are doing is 2 things seeing if the pump will build up more prerssure and verifying if the regulator is bad or not. If the pump can build that 40-44 psi then the regulator is bad.. when you pull off that hose see if there is raw gas in the hose if so the regulator is bad. Back to your origianl question stalling at idle I would look at a dirty throttle body or a idle control motor that is slow to react or dirty. Good luck :}