TPS voltage on 1987 XJS 3.6 on P system

Hello all new to site wonderful store of information.

I am part way through trying to resolve running issues with 3.6 manual on P system ignition. Getting surging when driving and lack of power when accelerating ok at low revs 5th gear will pull from 30mph in 5th no issue just feels like wrong fuelling. have been through all filters and flushed no change, have checked ignition all good idle is fine timing ok the issue is also random inso far as one day ok the other surging but will reach high speed. Have sent off injectors for clean await report However while doing that thought I would check TPS voltage so found getting no volts on idle and 0.1volts at full throttle on red and yellow wires however off green wire only 0.1 volts as a constant feed so TPS showing it only has 0.1v to play with? Disconnect ECU no volts showing so feed is coming from ECU this with ignition on no pump running as disconnected and fuel rail currently out for injector renewal. Given that a 5v supply is required and not being delivered it would tend to suggest this is the issue but not sure if all needs to be reconnected to obtain this 5v obviously 0.32-0.36v to set TPS cannot be achieved with this supply voltage. How else could the ECU be tested for 5v output? As a point of interest a recent repaired and updated ecu by specialist flooded the car out on idle cold start and ran like a kangaroo so is back for observation. Any tips appreciated.