Having some issues with Allison. 2001 CCSB, all stock, 247K miles. Getting codes PO732 and PO734. Occassionally the 1-2 and 3-4 shift will "flare" and then engage hard, all other shifts are fine, the more it is driven after it starts the worse the problem seems. Also there will be a delay from P-D and/or from R-D. Can shut off the truck for few seconds and restart and all is great for a few upshifts"varies" and then will start acting up again. Have been reading some posts on here and seems like CV1 and CV4 give some problems?? Not sure, would appreciate any input or experiences. Trans has never had anything done other than perodic maintenance nad pulls heavy loads almost constantly, total truck and trailer will routinely weigh out at 27K.

clutches could be getting burned.

The Allison was designed for 250K miles. Your at it.
Change the spin on and see if that helps any.

Fluid looks good and I change the spin-on and drain the pan and refill evry 20K since new. If the clutches are going and need a rebuild, why would it go back to OK after shutting of and restarting, would it not slip immediately on next shift?