Idle problems again

[Hiok-Tiaq Ng <htng@aries.ece.cmu.edu>]

Hello all!
	A while ago, I asked the same question about
a sporadic fast idle at 2000rpm and someone suggested
that vacuum lines could be the culprit. But the problem 
went away. It is back. The idle is now erratically
moving from 800rpm (which is the correct setting) to
2400rpm, stays there for minutes and at times a few
seconds and returns to 800 for a while(hours? minutes?
depends on my luck), only to go back up again. I know
it is not bad gas, as I have changed brands at least 3
times. Air filter seems fine and I took out the
throttle body to have a look at the air flow plate
(KE-Jetronic) and in was sitting correctly before and
after I cleaned it.
	It might not be a vacuum leak, but I am gonna
change all the hoses anyway. But is there anything else
I should look for?

Thanks in advance.

Tiaq
htng@aries.ece.cmu.edu