Thanks for all the replies and just a quick update that may help someone in the future
As said very simple job to replace injectors, I bought one from ECP as had a fault code on cylinder 3, replaced it and idle was better but EML came on soon enough.
Changed the plugs as the next step, again an easy job about 30mins and no need to remove the inlet and all associated pipework, just undo all the bolts and the grey sensor on the right of the plenum and with something to hold the plenum up there's enough room to just tilt it back without straining any cables or pipework.
Plugs on cylinder 1-3 looked ok actually but cylinder 4 was black, the electrodes on two plugs had literally worn away to nothing and when saw then had my money that the new plugs would cure the lumpy idle.....
NO.... no different
So back to ECP and got another 3 injectors injectors order in to collect a couple of hours later (negotiated a price of £30 + the vat).
Long story short, chucked em in, fired it up and like a new car, purrs away sweet as a nut.
So the spray patterns of one or more of the injectors must've been off after 140k miles so a job worth doing.
If you have a lumpy idle, defo worth checking injectors and for £30-40 each worth changing to rule them out.
