Hey, thanks for the response.

I will check the transmission fluid, but it really seems like it's shifting fine. No smoke whatsoever. No engine notification lights at all. My temperature gauge has been mysteriously dead for some time now, unfortunately, but the car is definitely not hot enough to lose any coolant or display any other obvious signs of overheating. Also, I've heard that a bad catalytic converter will glow red hot, but mine doesn't.

I still haven't ruled out the in-tank fuel pre-pump. Supposedly, if that pump's bad (either inoperative or just a clogged "sock), the car will run fine with a full tank, but it will start acting up when the fuel level gets low. I'm going to go fill the tank and drive up some hills to see if there's any difference in performance.

Again, much obliged for the input.