i found an alternate method of adding washers to the txs valve greatly helps smooth things.
essentially get a flat fender washer, ie, large outside diameter, small hole diameter, and put the spacer washers AND the fender washer in the CAP of the bov, not in the bottom of the piston. the fender washer goes on the SPRING side. the fender washer should be of an outside diameter that it fits reasonably snugly inside the bov cap. not binding, but almost. CAREFULLY put the top back on the body and piston.
such a stack limits the total opening aperture of the valve by blocking the brass piston's upward travel. this helps keep things smooth since normally the rfl vents a LOT of air mass, and with the restricted opening the bleed is a bit less immediate.
by altering the placement of the fender washer in the stack of spacer washers, you can change the ultimate opening size.
it's the only way i run my rfl nowadays. 4 spacers, fender on top of spring side, iirc.
also make sure your piston is clean, and the body of the valve is clean, and lube them with motor oil. i've found oil works out better than heavy sticky grease.