Don't know if this'll help, but....
I have a Ka with 130 000 miles on it and if it stalls between gear changes, or when coming to a stop - change the Idle valve. (front of engine - easy - two bolts and a push fit connector) Don't bother messing about seeing if it's ok, just bite the bullet and get a new one! - about £70 and it'll last about 70 000 miles unless you're unlucky. Don't buy a second-hander at any price (why would anyone sell one if it's not broken?)
If your Ka over revs between gear changes it's probably the throttle potentiometer - they become 'gunged up' with age, and are slow to 'return' under spring pressure - again, easy to do but this time it's two torx bolts (get the right size - they're made of chocolate!!!) and a push fit connector - found at the rear of the 'black box thing' on top of the engine - opposite end to the bit that moves (looks like a spring) when you press the accelerator pedal. This time you may be lucky - just take it off and soak everything in WD40 or oil, never mind what anyone says about it being bad for it - it's being bad anyway! Refit, and with luck you'll be OK - if not then buy a new one (not second hand)
Oh, and by the way if your brake fluid light comes on (but there's fluid in the reservoir) take the top off the reservoir and there's a spring loaded 'thingy' that pops up - this is held down by the top itself and if the push fit 'middle bit' of the top is loose it will give a false reading (ie illuminate the light). Just stretch some duck tape over the 'lid' any you're away (mines lasted like this for over 100 000 miles)
Hope it helps and good luck...
Les Fornear
Leslie Fornear, April 2006