Chevrolet S10

Hello, I hope and someone can help me I have a Chevrolet S10 mode. 1985 TBI 4 cylinders 2.5 motor and my problem is that when I have been starting a half hour that starts starting in each top of the semaphore Etz. It goes out to me already takes it to the Carburetors Hospital and the mechanic also the Czech and nothing found anything. They have already changed Cabes, full tuning gasoline pump, Map, well with the adjustment has but still the same I hope you can help me thanks.