RPM fluctuation "I need HELP"

[Impala SS '96]

Greetings,


My VZ LS1 5.7 SS giving me hard time lately with this fluctuating RPM. it happens when I change to/from Reverse gear. Or when I let the car drive on "D" without applying any fuel to the engine.

I consulted some friends & they told me that's VZ electronic throttle is very pron to dirt & dust.
and it's only a matter of cleaning the throttle body & the car would be as good as new.

I had My VZ checked in a nearby garage, the computer report showed that everything is normal, Except the desired "throttle position" it should be at 15% but my reading showed 18%...

To be honest I don't have a clue of the meaning of those numbers.

could you help me with your experiance & tell me where/what do you think is causing the problem?

Many Thanks In Advance.

[bludeck]

mine sumtimes does weird things like your describing but only in neutral without the a/c on. I cleaned my throttle body the other week which to my surprise was filthy only after 65 thou K. didnt fix anything but would def recommend cleaning your entire intake including throttle body.
Matt