Fiesta Mk4 1.25 Zetec 1999 - Fiesta power loss under acceleration - mookie

Hi,

When I'm accelerating through the gears the car feels hesitant and judders/struggles a bit, like there's a flat spot or some loss of power. It happens in 2nd and 3rd at around 2000rpm, speeds between 20-30mph. The speedo and tacho needles tend to dip when it occurs as well. It's fine in 1st gear and clears above 30mph and in higher gears. I'm not 100% but my impression is that it only starts happening after the car's warmed up, and not when it's cold just after starting. Could it be something with the fuel mix that gets hidden by the auto choke?

After a bit of googling I thought the problem was down to the MAF sensor, but turns out the car doesn't have one! All the little hoses coming off the engine appear to be attached and intact. There's no misfire as far as I can tell. So I'm after any other suggestions. I'm reluctant to just change plugs/leads/coil in case it turns out to be an engine management type problem. I'm also hoping it's something easy I can fix myself, cos I can't afford costly repairs at the mo'.

Thanks in advance.