weird boost problem ..

ca18det . i have a t28 bb and a greddy profec b boost controller. car pulls fine at base 6 or 7 psi when the system is off, fine at 9 the low setting and 13 the thing takes a quick nosedive at like 5 grand then goes right back to pulling hard…
i havent run the car since last yr on the higher setting, till the other day, and it feels like it looses boost for a quick second then right back. i coundt actually read the boost gauge when it happened becuase immidatley my eyes go to the road to make sure its still going straight.

things i have tampered inbetween last yr running high boost and the other day cleaned that idle valve on the side of the intake.
disconnected the battery , therefore having to reset the boost controller… was actually running 14 psi last yr…