1993 400e with the V-8

Can anyone tell me where a white plastic line goes? It's hard whitish plastic, very small diameter. Seems to attach to the intake manifold and runs somewhere behind engine. Won't let me post a pic.
Is this an exhaust monitoring item as it is running rich?
Vacuum for shifting?

trace it back, it should be going to the transmission, its what modulates how hard the transmission should shift.

a white line also is near the brake booster servo assembly which goes to the rear headrests. It branches off at a small T shaped manifold right behind the brake booster servo and goes into the cabin.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)