Need help with my 53 bel air

Hi I have a 53 that I have had for 15 years and my son and I put in a 350 and 350 ****** starts sounds strong has power I was driving it and drove fine but one day I just felt power going down I put the pedel to the floor and it just don't want to go I checked the timing fine replaced th coil and module but still the same so can some one help us us get our baby going thank you for your time and really happy to be a member