Rear Engine wants to Die!

[side241]

I have a '68 T337C that has 950TT, 100 time on turbo's. The engines start easy, good compression, and run strong. I use it to commute to work about 8 hrs flying a week, usually at 7,500 ft. During takeoff and climb, no problems. However in cruise, about every second flight or so the rear engine will start to die. Let me tell you, the first time was a bit nerve-wracking, but now it has become just an annoying source of concern. What happens on the rear engine, now that I have had a chance to evaluate it many times, is this: I will notice the EGT start to climb for about 10 seconds, accompanied by the fuel flow drop from 12gph to about 8gph. Then the rear motor starts to die, which I quickly remedy by turning on the fuel boost pump to high. Then I operate the engine with the boost pump on low, and it doesn't happen again. Only happens every other flight or so. I don't want to always use the boost pump, since I don't want it to wear when I might REALLY need it. It happens regardless of if I am on the mains or aux. tanks.

I have a few theories, but I am no mechaninc. All help appreciated.