ok, I thought injectors made perfect sense given the behavior and the results of the fuel pressure test.
But I installed reman injectors last week and it made no change whatsoever. I also fixed the exhaust leak (again, first fix failed) but it made no difference, other than eliminating that annoying click sound.
Tomorrow after I finish installing a power steering pump and new front shocks I'm going to test the TPS and MAP sensor. I tried to have it done today at AutoZone, but much to my surprise apparently they don't do that anymore. I guess the bean counters must have figured out that they would make more money if people just bought new sensors without testing the old ones. So i'm gonna have to buy a vacuum pump to test the MAP sensor.
If those are both fine, I'm kindof at a loss. With my vacuum steady and in spec and burning less than half a quart of oil between 5k oil changes it's hard to see it being a ring or other mechanical problem. The only electrical things left will be the coolant temp and oxygen sensors, which I don't think would be the issue since the behavior is present in both open and closed loop operation.