I'm assuming the mechanic is talking about the air sensor plate. It could be crudded up enough to restrict movement, or it could be out of alignment. If you lift off the top of the air intake where the fuel distributor is attached, you will see the plate. I would wipe it out instead of carb cleaner, and make sure the plate is aligned by running a strip of paper around the circumference: it shouldn't bind up anywhere. Lift the plate and check for free movement. A sticking plate, albeit rare, would cause low power as it would allow less fuel to the engine. The CIS injection system is pretty sturdy. I'd be surprised if this was your problem.

Charlie