Hi All,
My 2003 ST170 judders at around 2000-2500 rpm and then runs fine up to around 5000rpm when it stutters again then runs fine up to the red line. It happens in all gears but seems to occur when flooring the accelerator, gentle acceleration and it is not as noticeable. It seemed to start after a local garage serviced the car so I checked the plugs - they had fitted NGK's so I replaced with the Motorcraft one's - no change. I've had the error codes checked - none showing and I've disconnected the battery to reset the ECU but still no change. I've heard it could be the coil, fuel filter or the HT leads but would like any advice on likely suspects before spending any more - I've just replaced both front tyres to get it through the MOT!
Cheers

 

Fixed - took out HT leads measure the resistance - found them all checked out ok so put them back routing them carefully over the block - all running fine now so not sure what the problem was....