My SC seems to run a tad rougher once it's in open loop mode--I can tell the instant that it goes into open loop, because the idle runs quite rough with a bit of engine surging. After it's up to full operating temps, it's fine, but the car does have the occasional issue when starting it after I go into a store for a few minutes.

I'd changed the plugs (partially out of just wanting to change the plugs), and was going to clean the O2 sensor, but it's stuck. Judging by the color of the plugs that were in the car when I bought it, it's not running rich or anything, though when the car has the idle problems, there is a slight fuel smell.

I'd changed the cam position sensor, as well. Still the same result.

I'd noticed that the guy that had the car before me, had deleted the catalytic converters. I was thinking that this may be the culprit, though (if i'm seeing this correctly), it looks like there's only one on the '91's and that's on the passenger side. Could the engine be sensing what it perceives as a cat problem? I'm not getting any check engine light.