I would suggest you look at the timing VERY carefully. I don't know how fast the data is clocked in - I can assume it's from a 24 bit a/d converter - do you really need all this logic? Is the processor not fast enough to do some if not all of the work? 24bit a/d's are normally not too fast.

Also having monostables in a high speed digital design sends shivers down my back! A nice synchronous system is generally preferred.

Sounds like it's time for a logic analyser to see what your circuit is actually doing as opposed that what you think it's doing!!