Outer Limits 4x4 Board

I replaced the vacuum advance on my fj73 3F engine, and theoredically it should run better with more power and more efficiency. I only took it for a short run but the power was definetly less.
The car has been tuned for the broken vac advance, so would replacing it with a working one cause it run worse? or have i got another problem?

Play with the timing a bit and see how that works just small movements each way till you find the sweet spot or if you have a light you can play with it more acurratly