Very well could be it. The system will probably add fuel to the mixture somewhere before the mixture is dumped into the venturi or carb throat area. Probably not an additional hole in the venturi or throat area.
I can tell you've got the right attitude for solving your problem. You're thinking about it often and ready to get home and tear that sucker apart. I understand this, I just put a motor in my 240D (and after only 516K miles) and will probably get it started tonight. These projects are part of me until everything is worked out.
Don't turn loose of it's neck!