Volvo 760 Gle with PRV motor

I have a 760 gle volvo of 1985 with PRV V6 engine
the problem I have is that it stays a bit accelerated
to the engine several repairs have been done, but it continues a bit accelerated, and from time to time it goes down to its normal revolution.
The ignition is also difficult when the engine is already hot. The engine is very similar to the photo.

There is no photo attached to the post !!

But anyway I think you have an air leak in the intake manifold, or admission manifold joints, or vacuum tubes or something strange happens there ...

I suppose the engine is injection, what I do not know is the type of injection that it carries, I suppose (and it is already much supposed ...) that it will carry adjustments of CO and RPM to idle because it will not be a catalyzed vehicle, so it is possible that in the workshop it is possible that in the workshop Amount of gasoline that should inject the idle by the problem of improper air taking that I mentioned above, and now the engine is higher than normal.

The problem is that now, when he warms herself drowning gasoline because hot the engine needs much less gasoline than is entering to stay and ends stopping or costs it a lot to start.

Hang the photo so you can see the injection system, and where are the adjustments if it takes them, and see where you can have the possible air intake.

All the best.

The injection system used by the PRV engine is Bosch
K-Jectronic (CIS) mechanical injection system