car starts, runs for about 3 seconds, shuts down. have replaced coils

What is your question?

i have replaced the # 3 coil 3 times, last time about 3 months ago, all 4 coils replaced, now after about 2 months of driving, car starts, runs for about 3 seconds,then shuts down. ;mechanic has checked all of the obvious, he cannot figure it out, been in shop 2 months.