Bernie,

In this situation its usually because the WOT enrichment factor is too great and that at WOT the AFR is sufficently rich to reduce power output. If the map is running the injectors flat out and theres a significant WOT enrichment you'll probably find theres sufficent fuel for quite a bit more than 14psi. As Stu says though best to get it checked over, or if you prefer I can have a quick look over it for you at your place as I need to come down to see you soon. (Favours for favours)