I have been having some trouble getting my 95 Blazer to start and I need some help locating where the problem may be.

Background info:

-Last year I had starting issues, but that was electrical.

-Now it will turn over no problem, but it refuses to fire, not even a sputter.

-The fuel pump continuously runs after priming for a couple minutes even after the ignition is off and the key is out (the pitch lowers, so it seems to be running with less power than when it primes).

-In this cold weather, the car sputters to a start (when it works)

-The current issue started a few weeks ago and I switched the relays, it would start (barely) for a week or so, and this weekend its back to not starting (even with a new relay for the pump).

The Blazer does have over 200k miles and I am currently getting a knock sensor code and a crankshaft position sensor code. The knock sensor code I've had for a while and could just be a bad sensor (I have a new one ready to go in), but the crankshaft position sensor code is a new one (first came up a few months ago).

I would greatly appreciate any and all help with this. And if you need any more information, let me know.

Thank you!