My 96 2wd 6.5 Silverado has just been purring along until the other day. It sits more than it is driven

On a less than 10 mile trip to the office it cut off 2 times and hick upped one time all at low speed to idle.

Always started right back up.

After a few hours on the return drive I made one stop and pretty much kept her idled up and she seemed fine all the way home.

She has a new pump and a bumper mounted PMD.

In going through the records I see the fuel filter hasn't been changed in the year since I've owned it or in the past.

So I'm ready to drop in a new filter.

What I have observed is when I open the bleeder valve on top of the filter when running, nothing comes out the bleed hole until you open it all the way and then leaks out but still not out of the hole.

Checking the fuel pressure at idle its right at 3.1. Wth the motor off & the key on the pressure is more like 7 +.

The lift pump does not appear to be the original and no additional filters have been installed.

My course of action would be to get a new filter & check screen and retest.

Question: Should I consider upgrading the filter setup at this time or keep the OEM setup and ad a pre filter once I solve the problem?

Thanks as always