Neil - I've been familiar with these cars for over twenty years and never heard of the "Anti-Stall" valve. Perhaps you are referring to the Fuel Pressure Switch, attached to the outlet line of the Control Pump. This switch is there to ensure adequate fuel at start-up. The originals are no longer available, but there are several acceptable replacements. As for smoking upon start-up, this is certainly not designed into the EFI system. If you can't find this part, check back into the archives on this car - I'm sure there are several references there. Bob Harris