Boost Dropping Problem

[bobintrees]

To start, I have an 89 2.5 T1 with the mitsu. Only mod is a grainger.

I just put the g-valve set to 11psi in two weeks ago and it worked great for a while until one day it would spike and settle down to 5psi. Later that day, a few drives later, it would spike to 9 and settle at 7.

The next day in the moring, it spiked to 11 and settled at 9. Later in the afternoon, it was back to working fine.

I looked around a bit under the hood but didnt see anything.
A few days later a found and fixed a vac/boost leak.

After that my vac at idle was 20 and it boosted to 13psi. I thought that was the problem and was happy.

Well a few days later is today, where it was fine going to school but now it spikes to 9 and settles at 7psi.

Any ideas from the informed?
Thanks,
Bobby