hi ray/brian
been away for a few days hence late reply, thanks for the suggestions, as regards blocked exhaust have removed front o2 sensor as this had been replaced prior to me looking at car but made no difference.
yes agree fault with fuel/ or possible mechanical/breathing? I think from memory pressure was @35psi, have tried restricting both flow and return with no difference, have even removed fuel rail to see injectors work, still awaiting customer input as way to go.