As of today, it's been 10 days since my big car-repair project; on May 5th, the car's troubles finally reached a point where it stranded me on the side of the road on the way to work--just three weeks after stranding me in a Sonic parking lot at lunch.
Basically, the (computer-controlled) carburetor was letting too much fuel get by without atomizing it properly--raw gas was getting dumped into the engine and not burning properly, leaving a bunch of carbon and unburned fuel behind. It's a design flaw common to all the cars in the early '80s with that carburetor, and it's probably why there aren't that many Chevy Citations--let alone the X-11 "hot rod" version--left running.
I went to a junk yard, shopped around for a pickup truck with the same engine but no computer controls at all, and for $40 cash-and-carry I had a carburetor, distributor and ignition coil. I took my time tearing it all down, soaking it in solvent to remove 25 years worth of gunk, then rebuilding. Two weeks ago (May 21) it all got installed, but it took me a few more days to get the bugs worked out. On the 26th, I finally killed off the next-to-last bug and the engine started.
The last bug was the carb setup, but that was easy.
It's amazing how much more power--not a huge amount, but enough--there is. No sputtering, no stalling or uneven operation. When I want to speed up and pass someone, I just point the car and nudge the gas a little...VROOM! she goes.
At this point, I don't know whether I'm going to try eliminating that design flaw and putting the car back in original computer-controlled condition...or just leaving the computer stuff unplugged and driving it as-is. As far as emissions, it's exempt now that it's more than 25 years old.