And we have our XKR back!
AAA Davis Auto Repair pulled the fuel tank and replaced both fuel pumps. They found a pair of correct pumps as they did not want to do a cobbled together fix with spliced wires and modified brackets to fit a pair of "pretty close" pumps.
I did not know how the two pumps were controlled before this. Pump-1 is running all the time that the engine is on. Pump-2 only comes on with a certain amount of load or RPM. (not sure of the exact combination) So while we were blythely cruising along I80 on our way to Davis, CA, pump-1 stopped working. It did not produce any effect because pump-2 was still providing fuel at sufficient volume and pressure. (since we were not needing max fuel flow on the highway) At the exit, with the engine down to idle and zero throttle blade opening, pump-2 shuts off and since pump-1 was doing nothing, fuel rail pressure drops and the engine dies. Pump-1 was apparently only almost dead (see Princess Bride) it gave enough fuel to start the engine a little bit and get it off the roadway.
If I had known how this all worked before taking it to the shop, I could have jumped from the pump-1 fuse to the output of the pump-2 fuse and driven on my merry way, at least if I did not need full throttle.