89 honda accord idles low and dies in traffic

I have a manual fuel injected 89 honda accrod LXi. For the last couple of years it's had a problem where it sometimes won't start up, it'll crank but not fire up, or it'll fire up but within a second the rpm's just drop to zero. But after waiting a couple of seconds it'll start and be fine. It's also idled really low at times, maybe 500-700 rpm's.
Now i was driving it home yesterday and as i was going down a hill after a stop sign i had my foot on the clutch and it just died while in motion. Same thing when i was waiting at a light, i had my foot on the clutch and i just tapped the gas pedal so the needle jumped to like 1500-2000 rpms but instead of goign back to 500-700 it just dropped to zero. after that it would fire up but too low of rpm's and so would die within half a second, then after a few times trying to start it and waiting a few seconds i hit the key and the gas and it revved right up.

I've heard the starting issue could be the key cylinder? but what about the low rpm's and dying while riding???