Mine were fouling every 1200-1500 miles.Ordered the proper seal(4-5$)from my nearest dealer and no more issues since.
I am always on the lookout in the pick your parts yards for anything D-jet.My current work schedule(6 days/50+ hours/week) has seriously curtailed my parts hunting expeditions but I have had little to no luck finding these parts in quite a while.Fortunately my car runs pretty good,especially after finding a good aux air valve.Went through 3 before I got a good one.
I never thought about getting a spare ECU,,,Is this something to consider? I've not heard of one going bad but I suspect they must be in near "unobtainium" status.I have a spare set of trigger points and am going to get a MAP sensor when I can find one.