If the vehicle can be driven, but stalls at slow speeds and idling, cause may be mostly with the Idle Air Control Valve (IAC). If engine runs just okay without air conditioner on, and stalls with AC on, then the issue can be mostly with the IAC. There are no mechanical adjustments on the throttle for Idle, and the additional air for idling up is supplied through the IAC valve, with a signal coming from ECU. Since the IAC is directly mounted on the intake manifold, carbon and dirt can block the IAC valve passages over time and render it useless. To gain access, you may have to remove the intake manifold, which is not a very simple task either. First clean the IAC and check its function with power applying to its terminals (after removal). If IAC works well, then it can be installed after cleaning, but may have to replace otherwise.