[Bruce Edwards]

Most of them only have a sticker on them that is "Cleaned" off when they are rebuilt or cleaned and painted. I have seen some go for a long time and never get any worse. How many miles do you really put on your car every year? Most Cobra's are not driven that much so the problem can go on or years.
Still need to see if that is the problem. You really should drive the car with out the booster hooked up to see how the car runs. If you still have the same problem your 351 may have the floats in the carb set to high so as you slow down fuel is forced out of the vents and down the carb flooding it out.
When it dies how hard is it to start back up?