Have you tested the O2 sensors? Might even be cheap enough to just replace.

Plenty of diagnostics you can do...test fuel pressure, test O2 voltage, check vacuum at idle, pull the plugs and check for fouling, test for vac leaks, etc. Not sure if you can bench test those old TBI injectors bur st 175k they might be giving up too.

I did a quick skim of the thread, does this issue happen all the time or only cold/warm?

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Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth