I have a thread over on the W-Body forum, but I figured I would ask here as well due to the encyclopedic knowledge of all things GM. Plus that 3.1L is also found in our A-bodies.
So for some background:
I've recently got my 1989 Rega l3.1L on the road after sitting a while. It has been driving perfectly fine for a few weeks of intermittent driving. It's not my daily driver so I was using it for local errands. The other day it stalled as I was going up a hill and I was able to coast into a parking lot. I kept trying to restart it and it would catch and then quickly die. After about 15 minutes and multiple tries it finally started again. I chalked it up to old fuel and I topped off the tank with premium and was able to make my way about one mile home no problem. The other day I started it and it idled fine but as soon as I left the driveway it died. I rolled it back, and it's doing the same thing where it catches for a second but then stalls, but hasn't fully "woken up" again like last time.

I have good fuel pressure at the rail, about 40 psi, and as a quick remedy I tried throwing in in a new IAC valve, but that didn't help. I put in a new MAP, but that didn't help. It doesn't have a MAF sensor.
It ran for about 10 seconds today and then stalled so I clearly have spark. It also runs on starter fluid sprayed into the TB.

I'm not super familiar with the 3.1 engine, as my area of expertise is the 3.8 that was in my two Cieras.
It's a super low mileage (less than 70k w/ a broken odometer) engine and pretty clean.

Are there any common issues that would cause this?
See the video for what it's doing. I took the video before I changed out the MAP, but it's still doing the same thing. Also I guess the thing in the video I was unsure of is probably the canister purge solenoid.