As was stated unless you have something in writing you are probably out of
luck, trying to prove your case may be more expensive than the $3000 or
close to it.
I don't think you mentioned it but if you are bought from a licensed car
dealer you may get some mileage out of threatening to report them to the BBB
and the licensing board in that state, no gurantees, but some businesses
will try to protect their good name.
If an individual and not in writing it don't look so good.
I certainly wouldn't categorize this as a Porsche problem, any older car
bought sight unseen without warranty has a lot of potential for unseen or
undisclosed defects and a lot of "trust me" involved in the transaction.
But Porsche parts (and labor) aren't cheap.