Misfire in top gear only

Hi. I have a 2004 TD5 auto. On drive back from Manchester today it suddenly started misfiring when accelerating in top gear. Ok in other gears and even goes in to kick down and accelerates smoothly, however as soon as it changes up to top gear it rattles the whole car and loses power.
Car has 135000 miles and has Been well serviced through its life by its one owner before I bought it 2 months ago.
Any advice appreciated

Check the red plug on ecu for signs of oil contamination, if any present then clean connector and change injector harness.

Unplug the MAF and drive it so to see if it's better or not

johnlad said:

Check the red plug on ecu for signs of oil contamination, if any present then clean connector and change injector harness.

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Thanks for reply johnlad. Will have a look at the plugs on ecu. Would that give such a specific misfire as described.

sierrafery said:

Unplug the MAF and drive it so to see if it's better or not

Click to expand...

Thanks for reply sierrafery. Will have a look at the MAF.