Poor idle, rich condition – 2000 Acura Integra GS

Hey, new user here. Have a car I’ve been sorting out for a while. Recently replaced the VSS due to no speedometer readings and poor idle. Idle still poor after replacement, though car attempts to adjust idle. Smelled gas in exhaust and there’s soot marking the tailpipe (dark coloration on bottom). Not sure of cause of this condition, but the last shop to look at my car called it an “electrical nightmare” due to wire corrosion and ECU misbehavior. Haven’t checked the IACV yet, but smacking it with a hammer lightly has not changed idle. Throttle is clean. Only vacuum leak I can think of would come from the snorkel clamp having snapped, but I haven’t felt any suction from outside. Any clues, approach to this? Much appreciated.

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