Question on Fuel Pump and Filter Replacement

Hi, I've got a 2002 R53 Cooper S with 108k miles. I'm having a strange problem with gradual acceleration in lower gears 2-4. The power delivery is not smooth and it is 'stuttering'. This happens with about half to two thirds of pressing the throttle. However when using full throttle the power curve is smooth with great acceleration and no stuttering. I have changed spark plugs, ht leads, air filter and MAP sensor. The car engine now sounds much smoother however the stuttering that u get when climbing the rev range under partial throttle is even more pronounced!
Any ideas what this might be? Another forum said it could be the fuel filter, what do you think? Cheers

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[Nick at Pelican Parts]

Is the check engine light on? Sounds like an engine misfire. I would check spark, fuel and compression on all cylinders.


- Nick