Slow motion

I am new on this page and I still have a little lost. First of all greetings to all and thanks in advance. I have a Renault Laguna 1 phase 2 2.0 gasoline 115 hp 8v. When the car is slowing down it is stable, but the engine heads a lot even in recovery. I have changed the idle valve, but I have not reset the switchboard and the problem persists. My question is: will I have to reset it in a workshop? I do not know whether to follow for injector cleaning, change spark plug cables, coils, spark plugs, motor supports, lambda probe, various sensors, air filter ... that someone guides me please. Thank you!!!

Look I work in the official Renault workshop, in this case what I would

Thank you very much for the answer. Do you mean that you don't have to use the diagnostic machine and reset the switchboard when changing the idle valve?

No, it is not necessary to make a recognition yourself, disconnecting the battery for a minute, and then open and close the contact at intervals of 15 seconds about 4 times and already, but the nod that you mention does not imagine it as it could be more specific.

Thanks Kikemec. Well, the truth is that the idle is very stable, but the engine is as if it had the decompensated inertia steering wheel. When it is slowing down and cold it looks like a diesel and more seeing the movement of the gearbox. I don't understand it ... and on top of the slowdown to about 900 rpm and although it rises to 1100 rpm the nod persists.