First thing in the morning, and only when the gas level is low (before the light even comes on), my car seems to have a problem. Those conditions have to be met. Even after the first start of the day despite the engine being cold it does not do this:

As the temp guage starts to reach the warm level the engine begins to studdar... has a difficult time shifting down and then stalls out completly. If I pull off and restart the car it studdars at first and then clears right up and never acts up again the rest of the day. I talked to a highly educated back yard mechanic and he said though he knows nothing about imports, he suspects it is a fuel mixture system that regulates cold start to warm engine running that is not switching it over correctly?? Sounds like the problem to me but what should I be looking for to be replaced or fixed and ideas??

Thanks,
-G