You sure that the oil pressure doesn't drop when the engine bucks? ..that would be normal as the rpms drop when the engine bucks.

As for the bucking.. if the weber idles fine and comes off idle fine, then it sounds as though theres not enough gas in the float bowl. Either the floats are adjusted too low, or you don't have enough fuel pressure. If you have a fuel pressure regulator installed (which you should) you want it around 3 or 4psi.

If its too low, then the intake will draw more gas than the fuel pump is putting into the float bowl and if your at full throttle for more than a few seconds you won't get gas until the pump catches up with you. Same thing happens if the floats are too low.

Hope that helps,

Scerb