I have been having a problem with my car overheating when im not moving, as soon as the car is boosted the temp drops instantly, there is also fluid being pushed to the overflow but none being sucked back in, the rad cap has some pressure venting so im thinking that my rad cap is going bad but i figured i would ask you guys to see what you think.

I have a 97 honda del sol si turbo
motor is a d16y8

this problem doent happen all the time