Just keep playing the game and it'll slow down a bit. The stock coils were designed to play properly with typical crappy 90's operator maintenance, and they're overpowered when the game is freshly cleaned and rebuilt. Things should settle down after a couple hundred plays or so. Are the balls derailing off the center/right ramp wireform?
If things don't settle down, you can replace the flipper coils with the 11630 coils - these are slightly weaker and should fix the issue.