I have no ideas. But all i can say is: DAMN, my 2001 Targa is having a hard time surviving on it's way to 5,000 km! If Yours got over 20,000 MILES, you should be extremely happy with the way your Targa works, ever think of starting fresh, from say: 0 mi? It maybe the best for you, don't be affraid to let go, it may be the time. Anyways, good luck getting it started, I know how it feels to be in a stuck position.