91 civic with a b20b obd 1 rywire harness, b18 ecu(supposed to be chipped for b20)

So the problem I am experiencing from time to time is I will be driving and when I put it into neutral or clutch is the rpms drop right down all the way hitting the bar. The engine then feels like it wants to stall out and it revs itself a bit. Then it will idle very low at between 200-500. This happens once in a while. Then I am experiencing low or high idles. Then at other time I will idle at like 1000-1100 rpms. Then sometimes it just seems absolutely fine... What can I check to fix this problem?

Other than that the engine seems to run fine I drive it to work everyday, and it starts up fine every morning.