PLEASE PLEASE HELP ME

cossie has developed a problem, when driving on a small amount of throttle its fine,
but, when i give it some boot, it starts to run weird, boost goes all over the place,
and get this....... my rev counter goes mental, i'll be doing 3500-4000rpm
and the rev counter goes of the clock, the actual engine revs stay the same.
thought it might be ignition coil, so i tried a new one, no change.
any ideas guys....... pretty please