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