Update on the surging: It was, in fact, caused by a bad fuel pump. Near as I can tell, the pump was bleeding pressure internally. I got to this conclusion after checking fuel pressure and finding that with the car in gear and the engine loaded up, the surging would duplicate and fuel pressure would rise and fall in time with the surge. Fuel pressure was 35-45 and dropped to as low as 25psi. Then, with the system dead-headed (return to tank blocked off), when you would expect the fuel pump to crank to its highest rating it rose instead in steps, first to something like 50, then 60, 70 and finally 80. Curiously, after that, the surging disappeared, and when dead-headed the pressure would rise almost instantly to a full 80psi., leaving me with nothing else to conclude but that the fuel pump's internal pressure relief valve was malfunctioning. So, I replaced the fuel pump this weekend (what a PITA), and we'll see what happens. The surge is most certainly gone. Thanks for all the feedback.

Richard in Kansas
--
86 740T/87 745GLE/96 960 Wagon