I checked for leaks with propane and by inspection. There weren't any leaks (that I could detect). I ran he car with the mass air sensor disconnected. The engine seemed to run the same, but the car computer showed the Porsche Stability Management and ABS systems failed, and recommended I drive to a repair shop. I drove a good distance with the mass air sensor plugged in. On the flat at about 80 I normally get 26 to 28 mpg. I got slightly higher, 30mpg, but about half the miles were at 55 in traffic on aXXXXX It seems like some of the low end torque came back. The same hill the car previously stalled on it pulled up 35mph in 4th gear. It still seems sluggish compared to a few days ago.
I took the car to the local Porsche service center. They connected it to their OBDII computer. It showed a failure P1325 Inlet camshaft bank 2, intermittent, not present.
They think the problem cleared itself. It may be foreign matter in the oil fouled the hydraulic line to the cam timing adjust vane actuator.
Your advice has all been helpful. I'm new to JustAnswer. Do I owe you more than the original $15?
Thanks for your advice.