Negative, both of my s14's did this and neither one of them are haggard old pieces of shit. I'm 95% positive it has something to do with the ethanol content in the gasoline these days. To support my theory both cars were turbo, one was SR and one was KA using different injectors. Both cars do it worse when the gasoline level is getting low or after driving the car hard. One car it was so bad you can faintly smell it with the windows up. The other car you can only smell it with the windows down. It definitely has something to do with fuel though as the smell is isolated near the intake manifold. I went through this process like 5X with swapping injectors, changing o-rings, and re-sealing the intake manifold. 2 different engines, 2 different fuel pumps, 3 different grades of gasoline, 24 different injectors, 44 different o-rings, 3 different fuel rails, 3 different chassis, same result.

Shell gasoline was notably worse than other brands. My wideband would also go nuts during the rich condition reading 9-10 in boost instead of 11-12.