My civic which i recently purchased from a fellow DragVA user has a misfiring problem. It started when the seller had the car but was supposedly fixed. This is the thread pertaining to that. But now it has started up again. Here is the key facts about how it occurs. It occurs most at idle and under 2000 rpm. It also is noticeable upon accelerating, but usually isn't a problem at any cruising speed. Mostly just idle and under 2000 rpm and aggressive exceleration. Also what I noticed to be a problem was that putting higher octane gas in my car made it misfire worse. My car also does something similiar but, i think, unrelated. Upon start up it rev's up and down on its own, but not very high just between 900 rpm and 2500 rpm.

Here is what I've done to correct the problem:

I've checked the spark plug wires for integrity.

I've swaped out one of the spark plugs due to a different gap than the other three.

I've used injector cleaner diligently every 1 or 2 tank fulls for a month.

I tried cleaning the idle controller/(solenoid?) thinking it might be because of this.

 

Dirty fuel filter would be the most obvious problem. Either that or the pump, but most likely, it's just a clogged/dirty filter. You will get the exact symptoms you describe, because there's enough fuel for normal running, but when you need power for accelerating or any other load, you choke the engine.

Also just noticed that you use the fuel system cleaner, now I'm absolutely sure this is your problem! When you use that, it breaks up all the gum and gunk in the tank and sends it thru the lines, where the filter gets overloaded with it and clogs much quicker.

Easy thing to try and eliminate if nothing else! Let us know.

 

Also check your fast idle thermo valve, if it's stuck open then it's bypassing too much air past the idle air control valve (IACV) and making the idle wierd. You would only notice it at low RPM because it's such a small amount of air compared to what it needs under any kind of load. Does the temp gauge read correctly??

I have no idea what to tell you about the fuel filter, try that first, you should do that anyway if you don't know the car's history.