What's wrong when vehicle has difficulty backing up, sometime?

Hello, it could be a problem with the transmission - assuming automatic transmission - with, for example, a torque converter that is not disengaging, or a clutch set that is not working properly in the transmission resulting in a stall. It could also be due to load causing a poorly performing engine to stall, in which case engine performance testing is required. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops