Fuel pressure Problems

Problem: Glasair with I-0 360. With Vision Microsystem fuel pressure guage
and sensor.

My fuel pressure fluctuates from 23lbs down to about 10lbs and then back up
then to 16lbs and then maybe up to 23 for 15 minutes and then starts again.
If I turn the boost pump on it stays up to 23lbs.

I can let it go down to 10lbs or so in cruise but the engine doesn't miss or
quit.

I changed the Mech. fuel pump. It still does the same thing.

Could the pulse of the mech fuel pump be affecting the sensor?

Any Ideas or experience with this problem???


thanks

Steve