wont stay running

[DallasTahoe]

My tahoe has been sitting for about two months and i went out to start it, had to charge the battery upwhen i was able to get it ready to start, it would only run for about 3-5 seconds, everytime. I had this*issue about*5 years ago and they said it was something*having to do with*the*ignition*switch*not linking up, it had to be flashed or something like that, my question is, is there anything i can do without sending it to the shop again and*spending*$300 again????
Thanks in advance

 

[ccapehartusarmyINF.(ret)]

what year is the vehicle and turn the key all the way on without turning in over and see if you can here a whine of the fuel pump priming if you dont hear it its possibly the fuel pump id change yer fuel filter first

 

[DallasTahoe]

I thought that the first time it happened but after i had took it to the shop its some kind of syncing problem with the ignition