Every now and then on a long trip where I am averaging speeds of 100 - 110, the car will suddenly lose power and run rough like it is running on only 3 or 4 cylinders. When this has happened, I have pulled over and turned it off. When I restart, it is fine and stays that way for a spell then does it again. I know that that's not a lot to go on but does anyone have any ideas???

1989 260E

Most likely a lack of fuel..try a new filter?

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Vaccum or fuel leak ? Make sure there is no fuel smell under the hood. Also spray some carburettor or fuel injector cleaner in places where vaccum leak is suspected on the intake manifold, check all the rubber hoses for cracks. The computer may not be able to modulate the air/fuel ratio beyond a certain point and throws the car into a limp mode. O2 sensor wiring should also be checked for any signs of cracks or loose connections.

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Saumil S. Patel

Sounds like a bad air inlet MAF sensor.

Mine has started doing the same thing, except I don't ever get to go 100-110. It will suddenly lose power just driving along. Mine even does it sometimes just sitting at a light. It will suddenly start to idle rough, the idle speed will drop under 500 and when you try to move, the power is gone, like you've got five ACs running.

Turn off the key, restart and poof! It's back to normal.

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2012 E350
2006 Callaway SC560