hey im driving a rb20 with a turbo on aswell and im having an issue with an electronic boost controller, my solonoid doesnt regulate any air going into the turbo, but yeah mine was hiting fuel cut aswell and since i took the boost controller out of the mix it seems to be fine, might want to try that? take it out and if it stops doing that then its most likley a boost issue
hope that will helps in some way.