So a couple of nights ago I built a manifold for the fps on the quadzilla (I have access to hydraulic fluid fittings in all sizes) and was able to install my fps since I bought the programmer. I noticed the first night the pressure jumped around alot, and would drop to 6 psi on the gauge, then jump back up. I figured it was the water hammer effect, and I installed the needle valve I had bought previously but forgot about until then. 

She sits steady at 12-13psi idle, but continues to jump up and down while driving. I haven't romped on it (too scary to do with no 4x4 and icy roads) but it made me curious if the sensor was junk? Or? I also changed out both filters on my fass tonight just as a precaution (thought they might have become clogged from gel/sludge/etc) but no change. She runs very, very good now when I roll into her,but I worry about the fp. I go home Saturday night and have to drive about 900 miles (partially on deserted back roads) and I really, really don't want to break down. Thanks for the input in advance! 

More than likely it's the ball and spring acting up in the return of fass. You need to modify your spring to look like this.

The coiled up end goes towards the ball. 

Move the sensor away from the tap point at least 5 feet... Do not install the sensor at the tap point even with a needle valve. Electric sensor can't tolerate the water hammer pulses. 

 

I've got the needle valve and just after the needle valve is the snubber (sintered metal style) then 5 feet of tubing to the sensor posted above.