If the hose has an inside diameter larger than the steel tube it was supplied with there could be a variation in vacuum values.
Get a length of steel brake line and bend your own.
The kind with a steel coil on the exterior works best.
Get one that fits into the "L" shaped hose at the modulator.
The flare on both ends will make sure it doesn't fall off.
If the screw in the modulator is in too far it can cause a similar problem.
Back it out then turn it in until the end touches the diaphragm.
