Oy, my'84 245's been on a downward spiral over the last year. After replacing the distro with a pick-a-part replacement to rectify a Hall sender failure, I've had a persistent knock/low power situation, like the timing's not advancing properly, like the host organism is not happy with the donor organ. No real difference when using high octane. At idle, timing's set at 12 degrees and it runs OK except under load. I tried a test with the O2 sensor removed to see if the cat was blocked, and it seemed to improve, so I cut out the cat to clean it and temporarily installed a straight pipe in it's place.
Now I'm experiencing a sporadic no-start condition where it will usually start and run after it's been sitting overnight, but if it doesn't catch that first time, it won't start again until resting for hours, as if it's getting no fuel. Give it a long rest and it more or less wants to start, but again, if it doesn't catch that first time, you're completely out of luck: spark but seemingly no fuel. This is a very consistent pattern.
-Jumper wire tests on both fuel pumps seem to indicate them working normally.
-Fuel pump relay and fuel filter are new.
-Fuel level in the tank is down around 1/8, and no, I haven't opened up the tank to look at the pickup/sock, etc.
-Compression is good all around, and vacuum hoses are all new.
As usual, all thoughts are welcome.