Your symptoms are identical to those suffered on mine a year ago, it was always under deceleration that triggered the ASR light - see my thread a while back:
http://www.peachparts.com/shopforum/showthread.php?t=88071&highlight=ASR
In summery it boiled down to the cable setup and a broken cable jacket.
Check yours first before worrying about cable issues - but unfortunately these will be your next port of call as Justin mentions.
Lea