On my last two long rides, I had a cruise control problem that seemed to get worse (more frequent and consistent) as I rode. It got so that after about 5-10 minutes on cruise, it would pop out again. It would do this at different cruise speeds and while it initially seemed worse under load (on hills), it got so that it acted similar when not under load. It acted like I had cancelled the cruise setting. The on indicator light went off and the resume light came on when this happened as if I had hit the cancel switch. I could resume cruise but the problem would reoccur again after some more miles.
I read with interest dingy's post yesterday on cleaning the switch which I understand could help. However, could this be just a vacuum leak that gets worse depending on load etc. and if so, is there a most likely location for that leak?