we encountered a problem like this once before - it turned out to be the return line to the fuel tank was blocked. Please check this (it drove a mate and I mad).
I think that by trying to vary the fuel pressure between 20 and 40 psi would have answered the overfuelling issue (unless I am missing something).
The injector rap (tapping the steel body of the injector) is only relevant if the engine has been sitting for ages.