I, too, have this issue. [1999 1.25 zetec fester]

As yet, I haven' replaced anything....[except two new front tyres].

I presumed,because recently I'd changed my 'driving style' [drove somewhere else]....that maybe the engine management system had adapted to suit?

Of course, now I'm home, drivng style is back to 'normal'...

Seriously though....check out the power steering pressure sensor [somewhere onthe high pressure PS line?]

It 'appears' the connecting plug can become corroded, or damaged, especially if recently negotiated lots of water or grit.

This sensor works mainly to detect severe steering movements at low speeds/low revs/tickover. Such an increase in PS pressure might stall the engine, so the sensor tells the ECU to boost the revs a bit.

Also worth checking if the air con pump is actually disengaging when swtiched off?

[this also has a sensor to tell the ECu to load up to compensate for the increased drag]

For my normal gearchanging, the lack of rapid rev drop isn't noticeable.

{as above, I presumed the ECU had 'learnt' I like to block change my gears? ]

Or..am I just a confused auld fahrt??