Bouncing revs problem - VW

[okgo]

I've got an old polo, 1997 I think. It seems to be fine most of the time, it runs well, but after a little while of driving it starts dropping off the revs and then going back on (at speed), and when you slow down and knock it out of gear the revs seems to go back down to idle then bounce back up to 2.5k and it goes up and down like a yoyo...

I managed to stop it a few times by revving it to clear it, and it stopped, but it did it 2/3 times on a 2 hour drive...

Any ideas?

[Choppers]

I had a similiar problem on a 98 16v golf gti, it turned our to be the cam sensor. It would be worth while looking into as mine would only occasionally do it & then one day it just cut out, wouldn't start & had to be towed

[mwcr85]

I think the engine speed sensor for the Polo of that vintage is in the distributor, I changed one last week on a dead Polo.