Hi
I think you could show this quite simply. If you use expansionary fiscal expansionary, i.e. increasing govt expenditure and reducing taxation, this in turn will lead to a larger budget deficit. Some argue, especially monetarists that this will lead to crowding out, basically because of the increased govt expenditure, private sector will fall and higher govt borrowing will push up interest rates. AD could therefore fall to the left.
You could also look at the elasticity of the AS curve to upwards shifts in AD. The greater inelasticity of the AS curve the greater the rise in price level for a smaller rise in output. You could look at trade offs.