while driving at a steady speed between 50 to 60 mph the engine starts to hesitate & hold back. car will accelerate OK with no hesitation, when started from cold this also occurs more noticably until almost up to normal running temp. any body got any ideas? car is a mk6.5 zetec

 

First step as with any modern car is to get it on IDS (Ford's diagnostic system) and get fault codes read. It could benefit from a later PCM calibration, if there's one available.