shuttering on hard acceleration

[chx_wagon]

car shutters quite bad some times on hard acceleration what could be the problem? My parents have a 2.5st and it is doing the same thing

[godzilla]

Manual or auto?

[chx_wagon]

Manual or auto?

Both are auto tiptronic

[Subaru ETA]

i assume you mean shuddering?

if you put it in drive and load it up with your foot on the brake and accelerator does it do it?

[bradc]

If it happens at low rpm's and in high gears it is most likely the wrong gearbox oil.

If it is at higher rpm's, say from 4000rpm upwards then I'd be looking at plugs or coil pack (in the ST-R the distie)