I'm new to this list and hope I can find help. My '87 190dt (325000 mi) 602 engine, started surging at highway speeds. Cruise control is inoperative. EGR system removed years ago, "motorized flap" assy. in air cleaner housing tossed years ago also, throttle linkage lubricated, filters changed, good vacuum, no visible fuel leaks. Started surging at 65 mph requiring constant footwork to keep at steady speed. Disconnecting ELR actuator drops the idle speed but surging remains. Disconnecting ALDA corrects surging but, of course power is gone. Adjusting the ALDA one turn in or out raises or lowerers the surging speed (and power) but it still surges. Removed ALDA, opened, all seemed fine (seals & bellows) flattened cover and housing, resealed with silicone sealant under and on gasket ring. Still same surging problem. Tried without wastegate hose, same. Suggestions?
Thanks