MGB Gets too Much Air

I have a 1980 MGB with a weber DGEV 32/36 carb. The butterflies stay open all the time. The car runs good when they are manually held closed but when allowed to open the car runs poorly when warm outside and kills if it is cold outside. This is after the car has time to warm up. Any ideas on how I can fix this so it will run good when the butterflies are open?