Finally had some more time to work on it. 2 mechanics suggested fuel filter or pump. Replaced screen & filter (fuel pump "body"), no change. New fuel pump, no change, grrr. [anybody wanna buy a fuel pump assy?]
008's comment on MAF jarred my memory of an erratic MAF on a Mitsu pickup I had years ago. That was a $180 part, ugh. So, unplug MAF, test idle, still bumpy. Until I turned the a/c off. Suddenly no bumps. Huh? [If you've kept up, it's always been WORSE with a/c on, but still bumpy with it off. First eureka: stop using the a/c, it's adding another variable. But dang it's hot right now...] So plug MAF back in. Still no bumps, no way. Test drive, no bumps! Even with a/c on!?! WTH??? It drives great. For 2 days, then back to the bumps, with or without a/c, sigh. The last thing I did before it temporarily cleared up was idle with MAF disconnected. Try that again, still bumpy. Maybe MAF is schizo. Buy a new one (only $30 this time thank goodness). Just put it on. Drum roll...........no change. [anybody wanna buy a MAF sensor?] I'd kill this car if I didn't love it so much.
bbbalace1 thanks for the VICS tip. I'm not getting any codes other than the random misfire when it does a super-stumble. I've read up on VICS and VTCS and it doesn't seem either of those could cause this problem, buy hey, I think I'm out of reasonable conclusions, so need to investigate.
pcb, you listed the components that the ECU uses to control idle. I'm most suspicious of the two temperature sensors, only because I never get the bumps within the first minute of running. Will be investigating those too.