Yes, change the filter then re-test. If that doesn't fix it and you replaced the regulator, then the next thing on the list is a leaking injector.

 

I assume what you mean is it goes to 55 for 2-3 secs and soon as the fuel pump turns off down to 0 within a few seconds.

With that upper manifold off, turn key on and look for any signs of fuel leakage. Dont forget, if the connection on the gauge leaks at all that will fake that leakdown problem.

Hmmm seems to me I said 'change the fuel filter first', several times. Now you want me to say it again? It's too late.. you changed the pressure regulator first.

Now you need to test the pump for deadhead pressure and leakdown at the filter connection.
Go here and scroll to bottom for directions:
https://blazerforum.com/forum/tech-a...agnosis-23038/

 

ok im new here so i really dont know where to ask questions lol..but i have a 1999 chevy blazer that started bogging out when i press the gas..Ive heard maybe it could be the fuel filter can anyone help me with this please?