I have a 2005 Forester with 172k miles on it in Boston. In October (3 months ago), I was having some issues with the engine stalling when it was rainy out. I could get the car driving, but once I would get up to ~2500 rpm in the rain, the engine would sputter and lose a lot of power.
To fix this problem, I changed out the ignition coil and the wires to the spark plugs. I used Duralast parts for this. This seemed to fix that problem, but a new problem arose.
Since swapping the coil and wires, the car will oftentimes not start. It will crank and crank, but will not start running on its own. In cold weather (less than 20 degrees F), there is not really much of a chance it will start. In warm weather, it will start sometimes. Hooking up jumper cables to another car would help sometimes, but not always.
I have since replaced the spark plugs and cam position sensor (1 of 2?), which didn't help at all.
I had the car towed over to a mechanic who tried diagnosing it for the last two weeks. He discovered that when the issue was happening, there was no spark. However, he could not figure out what the issue was. He replaced the crankshaft sensor, but that did not help either.
In week 2 (last week) of the car being in the shop, the car was starting up every time. I picked it up and drove it home with no problems since I need the car for work. Ever since then (2 days ago), I am having the same issue again and have not been able to get it to start a single time.
At this point, I am thinking perhaps it is the wiring or the connector to the ignition coil, the ECU, or perhaps another sensor. Before I try poking around in there some more, I am hoping someone here might have some advice on this case.