First off i have a 98 civic with a 94 gsr swap.
I got stranded leaving IA saturday because all of the sudden my rpms just dropped and started going all over the place. I turned it off and then started it again. The rpms would hiccup a bit and then drop all the way down and eventually die. Even if you hit the gas it wouldnt do anything at all. So we let it sit tell sunday when we came back. I had an obd2a p72 in the back seat so i swapped that out with the jdm obd1 that was in and it seemed like it worked for a second and then started doing the same thing.
It has done this before and it almost seems if it sits for a while it will get better. But this time it seems like it is still not running right.
Some people have said the ignitor/dizzy, some said the fuel pump, the tps, or even the main relay.
So what do you guys think? I don't even know where to start.

 

Also when i switched the ecu i was able to rev it up a bit. But I'm not sure if it was just cause it was sitting for a while or not. But if i held the rpms at a certain spot it would all of sudden drop real fast and then go back to where i was holding the gas at most of the time.

 

And some times before this was happening it would seem to bog in lower rpm's after i got on it, but that would go away too like over night.

 

Any CEL codes? Have you checked the mechanical timing to see whether the timing belt skipped a tooth?

How old are the plugs, wires, cap, and rotor?

 

The plugs and wires are pretty new. The cap and rotor i'm not sure.
The only CEL that is on is the IACV and that has been on for a while and never affected anything except it idleing low. And when it does run good for a minute or so it runs fine, so i wouldnt think it would be the timing. The timing belt isnt more than two years old.

 

Definitely first check the cap and rotor. Also check the ignition timing with a timing gun.

Pull the CEL codes to see whether a new code has appeared. This is the problem with not fixing CEL codes -- you don't know whether new codes pop up.