85 250sx no-start after timing chain replacement

[lowtoe]

As the title says, I replaced my timing chain, and now I have an issue I can't pin down. It will start and run for about 5 seconds, then stop suddenly. Then, if I try to start it again, it will pop but never run and then the starter will turn the engine over slower and slower until it wont turn over at all. Interestingly, if I come back hours later, it will turn over fine then bog down again.

I tried my very best to time the engine correctly, and it kinda runs and easily turns over via a wrench on the flywheel, so I don't think I messed up the timing, right? I also checked the battery voltage and it's still at 12v.

What the hell could be causing this? I find it very weird that it turns over and fires one minute, but then doesn't the more I try it.

Any input is appreciated, thanks!