VS Troubles

Hi i own a vs commodore and am having trouble with it when driving if you plant your foot it goes normal but when you let your foot off the pedal then put it back on there is nothing the engine seems to go into limp mode and will only travel at 20km/h until you stop then the same thing happens again can you help me ?

Have the harmonic balancer rubber checked.

Seems like all vs's have problems How many kms has it got on it?