To check fuel pressure:
Fuel Pressure - Checking
Not sure if this would rule out a partially clogged filter and fuel delivery problem but a good place to start.
Vacuum line routing here:
Fuel and Vacuum Line Diagram (1985.5 and Newer N/A 944s)
If you have a fuel pressure gauge that doubles as a vacuum gauge I think it should read around 17 Hg at idle.