PoetinSF, I'd be interested to hear about your induced microcrash theory. My trouble with pacing is, my ability to do any given activity (say standing up to wash dishes, or moving things around my garden or even just walking up a hill) varies from week to week, day to day, sometimes even hour to hour. And I think this is true for most of us. So I'm constantly experimenting with how much I can do without bad consequences - and constantly getting different answers.
Sunday, perhaps experimenting too much is not that meaningful if you can't take care of daily activities like doing dishes without bad consequences. Best thing to do probably is to break up those activities in conservative blocks (say, a few min at a time), stay there long enough to make sure it doesn't make you crash even in your worst days, then increase slowly till you hit the greatest lower bound of your variable upper limit. (Tho, I started walking in 2008 when I was pretty sick, when I had trouble bathing at times, because I had to get out of the house to stop feeling so effing bad).
Strangely enough, I found my upper limit to be stable and precise as long as I don't have major crashes. For example, I can do 2 x 1mi slow walk with 30 min rest. 10 min session with 10lbs weight, on the other hand, will reliably put me to bed the next day. This limit hardly budged after well over a year, though it seems to have started to improve finally. I recently discovered that I could walk off crashes that last no more than a day or two, so I started inducing microcrash by doing weights a few minutes and then walk it off the next day. It seems to be working so far, but it's way too early to tell if that'll indeed help me increase my limit.( And, without controlled clinical trials, the improvement could well be despite of it, not because of it).
That said, I'm probably further along than most of you. (I'm still at 20% of my previous ability, but I'm no longer sick as long as I strictly stick to my program, unplanned out-of-band activities notwithstanding.) So what I do may or may not apply to your situation. But I would still recommend giving a try to Bruce Campbell's guideline that Andrew posted. My experience agrees almost entirely with what he says there.