Intermittent #2 cylinder?

I have the vehicle listed above DOHC sat that I got cheap, of course smog is the reason. So, the guy says he replaced everything but the knock sensor. So, I'm a mechanic sort myself and this car is a weirdo. Can you believe after checking the compression and fire and fuel the only one is fuel it came down to, because great compression and fire. So, I did a basic test on the injector, and it half checked out I get 12v and thought I heard it click doing the ear test. So, while waiting for an injector to come in, I checked the grounds and pulled the computer up to make sure the plugs were tight. So, the next day I'm driving now and it seems to run great. I didn't feel a miss, so I pull over and pull number 2 wire and bam the darn thing is hitting, all my cylinders are back. I was so happy, so I figured must of been the comp plugs and #2 injectors is now shoot gas. Anyway, my lady drives it work and back the next after me running around all day on four cylinders and I get in it and bam, right back to the same stuff. I'm asking if a stuck valve could go in and out like that. Because the of to me the only the left that could be intermittent. Thank you