This would be the long way around, but the current version of Melodyne(outside of PT) can be used to smooth out tempo fluctuations
(and boy I feel your pain
). Sometimes, as a musician/engineer, I have to simply bite my tongue and let something sound like the players played it and give up on my idea of "right" or "perfect"
Back to Melodyne for an example: A friend's band uses some backing tracks in their live show and he had downloaded a midi file for a song and the midi was done to the original recording(with every tempo discrepancy included). At the gig, all the players had an awful time trying to follow the click that followed the track. I was able to drag the track into Melodyne, which analyzed and showed the erratic tempo, which I was then able to smooth out(probably went about 90-95% flat) and that made a huge difference for the band(of course, it would be best to fix the drums before anything else got recorded
)