For clarification, the condensor motor is a separate motor from the evaporator coil motor.
The motor you have now described is in the air handler section of your system.
Even if the motor has been replaced once already, the specs on the second motor seemed to work for awhile but, as you indicated, if you can get the specs for the OEM motor, you may find the cause for repeated replacements. The motor itself may not be bad but, the thermal overload switch might be bad/weak. Your other option is to up the HP on your next motor, probably by a 1/8hp or so. Any larger and you'll be looking at increased amperage.