Crankcase (pcv) Problems of Subaru Legacy

I have a 1996 Subaru Legacy l with an intermittent engine miss with a p0304 (miss in cylinder 4) code. Most of the time it runs fine but when it misses, it is very violent. It seems to resonate. Changing speed usually makes it go away. When it first started, it only occurred once a month. Over the past year, and after several mechanics visits, it now occurs nearly every trip. I have replaced spark plugs (yes ngk), spark plug wires (Subaru original equipment), gas filter, air filter, coil, pcv valve, knock sensor, cam and crankshaft sensors. The injectors have been swapped between cylinders. I have been to an independent mechanic twice. On the second trip he gave up and advised I go to a Subaru dealer. After two visits to the Subaru dealer, I've spent several hundred additional dollars and still have the problem. They replaced plugs, knock, cam, and crankshaft sensors. Doesn't Subaru have diagnostics to identify what this problem is. I took the car to them with the expectation that they could identify what is wrong instead of just replacing highly suspect parts. They don't seem to be doing any better than I have done on my own. I've seen others post problems here and at edmunds with driveability issues. I've never seen a posting that indicated it was actually solved. Surely Subaru knows about this problem and has a fix. It has gone from an annoyance to a safety issue. Does anyone have any suggestions? are some Subarus just lemons?.

See all problems of the 1996 Subaru Legacy 🔎.

During routine oil change mechanic noticed crankcase leak. Went to dealer who told consumer all 3 of their vehicles do that, seemed like a design flaw. A crankcase seal failed causing crankcase leak.

See all problems of the 1997 Subaru Legacy 🔎.