Load up a Default Cessna 172.
Start the engines and look at the engine Tachometer.
At your minimum throttle setting is should indicate idling at between 600 and 800 RPM.
Apply full throttle, with the brakes held full on, the reading should be around 2,700 RPM.
Close the throttle, and the reading should slowly drop to 600-800 RPM again.
Your taxiing RPM on the ground should lie between 1,000 and 1,200 RPM.
If that is successful, then you have your "throttle/speed application" problems elsewhere...

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Paul...G-BPLF..FS 2004... 8-)...!
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