[JWalsh]

I have a mechanical fuel pressure gage with an isolator installed on my 1994, 4X4, 5 speed. Since installing it about 6 months ago the fuel pressure read constant between 19 psi and 25 psi depending on the engine RPM. Now for the past few days in the morning it is still constant but in the afternoon it oscillates so rapidly around the above pressures that the needle is a blur. It also seems to be getting worse. Does any one out there have any ideas? Any help is appreciated.