i have a isspro fp gauge with isolater and snubber and it takes about 2minutes
to come up to normal pressure [25psi] then stays there with no flux.
95 12v 168K stock, is this normal

 

If the gauge is dampened so it doesn't pulsate badly it will also be slow to read, but not that slow.
Ones I've installed with a needle valve almost closed to dampen take about 15 seconds to stop rising on start up.

What you have isn't quite right but I wouldn't worry about it.
Bigger problem is the isolator, seem like most folks end up eliminating them due to inaccurate readings.

 

thanks for the info i was thinking of losing the isolater

 

removed isolater,all is good