The GTi is still playing up, it's been into Fords more than it's been on the drive recently and they can't fint a fault!!!

The car starts fine, runs fine, but when driving it reaches about 3000rpm and starts to cough and splutter, this clears if you put your foot down a bit, but as soon as you reach 3000rmp in 3rd 4th and 5th it splutters and feels as if it wants to die, the exhaust also gets black very quickly when it's doing it like unburnt fuel??

Any ideas would be great

Cheers

Jobbo.