Welcome back Hummingbird
So did you really sleep through winter? If only I could...
Daox is right about the additional vacuum tank. A vacuum pump is unnecessary since gas engines produce vacuum anyway. Diesels, on the other hand, need a pump, so they would benefit from switching to electric (on my to-do list). This would not only be much more efficient (as you noticed), but would also allow the pump to kick in when EOCing.
Ben used an electric pump because that's the only way to produce vacuum in an electric car.
Also, inspect your vacuum lines to make sure they don't leak.
Here are 2 links to DIY vaccum tanks:
Homemade PVC Vacuum Reservoir
Auxillary vacuum reservoir
BTW: Just a thought, but would it be possible to create vacuum
while braking? Something like a mechanical pump in the wheels, replenishing your vacuum while you use it!