I store my Elan over the winter & have a few issues with initial rough running which I always put down to this dormant period.
This year, I pulled my petrol lawn mower out of the shed and it too run rough/cut out etc. I mentioned this to a friend who mentioned that modern petrol is known to oxidate alot quicker these days and that if I ever planned to store my car/mower for any period, I should add a fuel stabilizer.
I bought some of this stuff, drained both tanks and gave it a try, to my surprise, both my mower and Elan run perfectly (starting first time, after initial priming) after being stored for 4 to 6 months.
http://www.thefarm.org/charities/i4at/surv/sta-bil.htm
So if your Elan is being stored for long periods, then it's almost certainly 'collecting' water, so adding some of this stuff can't hurt.
It doesn't effect emisions or the running, as my car flew through it's MOT with this stuff in the tank.
Rgds
Darren.
For those that are interested in the chemical process
http://www.tfd.chalmers.se/~ogink/HCCI_chem.html
Open mouth, insert foot.