The problem might simply be that the pulses are hitting high pressures and fatiguing the reasonably flimsy evap cores.  There's also the possibility that the pulses hit a resonant vibration at some point, which causes the failure.

It would be interesting to see a trace of these pulses, and they may be important; but I am skeptical about them being the primary cause unless your cooler is near the engine outlet, and you have rigid (solid metal) lines.  These pulses are high frequency, and would not be expected to propagate well in a somewhat viscous fluid and flexible lines.  The pulse energy is dissipated along the way with the energy going into the fluid.

The existence of resonances is questionable for the same reasons.  Self damping.

I can put my hand on the line or my cooler tank with the engine running(with a glove on, of course) and feel no trace of any kind of vibration.  But, there is a couple feet of steel braid flex line, and dual filter unit between the engine and the cooler, and a robust cooler; so this may not apply.

Al