1967 vailant

need help i have a 1967 vailant i bought recentely it started out running fine but when you floor it it didnot sputter or carry on it just did nothing would get up to speed but not verry fast i thought it was timeing note the car has been comlpety rebuilt everything mechanical and electrical is new yesterday i went to fire it up to put it in the garage to start diegnosing the problem and now it will not run at all it will run for a couple seconds and verry shitty at that it ran great the day before but today it does not i tore the timeing cover off and all timeing is fine so im baffled any help would be great thanks