Buick Regal dies

I have a 1993 buick regal 3.1v with 200,000 miles. Whether idling or at 50 mph the car will attempt to die or stall, but definitly dies at idle intermittently. It doesnt matter if hot or cold, and when it dies the rpm guage sometimes goes up quick then to 0 rpm. It usually starts up again, but lately it cranks over longer untill it starts. If I run up the rpm to 1500 at idle it still wants to stall but I can keep it running longer at a traffic light. There are no ecm codes stored. I replaced: crank sensor, ignition module, spark plugs and wires, iac motor, and all vacuum hoses when I took off the upper plenium to clean it. Maybe its the cam sensor but I cannot find it. I also looked at the rail fuel pressure by barely pressing on the valve you use for testing so a stream would be present and when the car died the stream was the same comming out, so it might not be the fuel pump. Please help, thanks[/b]