I've got a weird pressure issue that has just developed. Under normal highway driving - tank is full & throttle at a constant position - the fuel pressure starts at 15psi, slowly builds to 20psi - over about a 2 minute period - then snaps back to 15psi. It happens like it's spring loaded - literally pops back to a steady 15psi. It then starts again & repeats the issue - over and over again. It's freakin' me out!

Pump & filters are less than 3 months old. Draw straw is installed.

Any ideas?