GTP stock boost gauge problems

[GTPer]

Hey guys I have a problem with my stock "boost gauge". Sometimes when I first go start the car when the engine is cold the boost gauge on the DIC reads half sometimes 3/4 boost at idle. Then when I actually start driving the car I barely have to touch the throttle and the gauge reads full boost. I'm not sure if it's the gauge that's reading wrong or if the car is actually holding half and 3/4 boost at idle and giving full boost at any throttle position. It happens every now and then. I really want to fix this issue as it is an annoyance for me. It's a 97 GTP. Thanks.