Your opinion on a class of ODE problems

[ttw]

If you are not using a canned method, you might try deriving a method using 3 steps so that A is updated on steps 1(mod 3), B on steps 2(mod 3), and C on steps 0(mod 3). This type of overlapping update has helped in dynamic equations. Of course, (as I didn't derive anything), the error terms would have to be worked out.