So after some more testing today on the car in my previous post (https://honda-tech.com/forums/showth...1#post39864101), I've found a few things.

The car is staying running indefinitely, and it starts right up, the hard start might have been because the guy I bought it off of flooded out the plugs trying to start it (he had the pedal to the floor).

However, after driving it up and down my mother's alleyway I discovered the problem with the transmission. It drives fine, shifts fine, however shifting it between drive and reverse a few times after it's been warmed up and the car won't go into gear anymore, so that's weird. However, what makes it weirder is that when you stop the car, put it in park, turn it off, start it back up, and put it in gear, it goes in. Is this a fluid problem?

I have checked the fluid warm, and it's within acceptable parameters, but is it possible that it's lost viscosity and that it needs a flush and new filter?

When cold the trans drives and shifts fine, not even the hard bump when going from 2nd to 3rd like a lot of these get. To the best of my knowledge this was owned by an old lady, then a guy who didn't know anything about cars (hence probably why he had the pedal to the floor trying to start it). So the trans has probably never been flushed or had a new filter in.