i have a 91 rs. when i check the fuel pump pressure it reads 9-10 lbs. when i check the actual fuel pressure it reads 10-11 lbs, would it be a bad pump or regulator?

 

where exactly are you taking the pressures.

 

the inlet line by the alternator

 

i removed the rubber hose from the fuel line and connected an inline gauge

 

seems a bit low. A TBI rebuild kit isnt expensive and could be the cause.

 

Is this tread about the same issue you posted about in the previous tread? https://www.thirdgen.org/forums/tbi/...-way-rich.html

Stock fuel pressure is around 10-13 psi on these cars and the fuel pump should push at least 15 psi.
If the fuel pump only produces around 9-10 psi, as you described, it is time to replace it.