Why do my windshield wipers park in the middle of my windshield?

Apparently you have an alignment problem with the blades. I am including a article about this that may help you. Ralph.

You said you just replaced the motor... sounds like you have it a few cogs off on the gear on the motor shaft. You may be able to loosen the motor enough to move the wipers to the proper parked position (without turning the motor shaft) and then put the motor back in place. Then you should be back in sync.

General Motors also has problems with the pulse board module. I have witnessed several cases where an owner thought the wiper motor was bad, and replaced it, but the pbm had also went kaput at the same time. Most FLAPS (Friendly Local Auto Parts Stores) will stock them in new as well as remanufactured versions.