I cannot help you on the first stall, but after that, your problem was what is called - lawn mower syndrome - trouble starting the 850 engine after it ran for a short time.

Named for moving your car to get the mower out, then the car won't start again.

If you have the car towed to a dealer, they will start the car, change the oil and filter and put new spark plugs in. This is because there is an extra fuel condition when the car is hard to start, and this can foul the plugs and thin the oil.

If you observe carefully, the motor will actually turn over a little bit faster during this condition and try to start.

There are several theories as to the cause of lawn mower syndrome - most relate on how the valves stick open, causing a lack of compression.

My take on the situation is that the first thing to get warm when the engine starts are the valves. This causes them to stick in their guides, causing the lack of compression.