E300D intermittent hesitation/power loss
'98 300 E TD. Engine hesitation occurs intermittently. Can be very frustrating, leading to total loss of power. Happens at any speed and any RPM, but only happens under load. Burns perfectly clean & smooth, but hesitation is a big problem. Comes & goes w/o reason - might hesitate badly for 5 miles or for 1,000. Might happen every drive & repeatedly for 2 or 3 weeks, and then might run perfectly for next 2,000 miles. WTF?! Have checked for codes, good fuel flow, mass air, etc. Is confounding to all mechanics I've brought it to.