here's another thought on the rich fumes,,,,
possibly a cracked diaphram in the fuel pressure regulator. That would allow gas to be sucked into the plenum.
Pull the vacuum hose to the F.P.Reg off on the back side of the plenum and see if these's gas or strong fumes.
The F.P.R. sits between the plenum and the firewall near the trottle body.

dave h.
'89 Raider V6 5spd;Aisin Hubs;; Gen2 LS: frt. brakes, rear coils;U.C.arms;R.trailing arms;idler arm; rear LSD axle w.disc brakes ;2 battery system for Dog's fan; relocated ECU; custom bumpers;J.Baker receiver;Conferr roofrack; t-bar crank.