I recommend checking the pressure in the fuel rail and replacing the fuel pressure regulator if it has not been replaced already. As the other members mentioned everything that has rubber components will age and deteriorate even if the rubber parts are I internal components such as the diaphragm of the FPR and fuel dampener.
Dimi P.
flyinghorsemotorsport@gmail.com
1986 Porsche 944 (3.0L 16V Conversion) - on track duty!
1989 Porsche 944 $2 - for show and fun!