Not sure on the fluctuating idle, but without an MAF signal the ECU should drop into a base map to keep it running. It might not be able to rev above a certain point without a MAF as well
------------------------------------------------------------------ 1992 300ZX NA 5 Sp (Dead) 1990 300ZX NA Auto 2+2 (Dead) 1990 300ZX TT 5 Sp (Est. 400 HP) 1990 300ZX TT 5 Sp (Est. 600 HP) 2004 G35 Sport 6MT (DD)