I have a 92 civic dx, Randomly on the way home it started to run really poorly, mis firing shaking etc. I got it home and when the transmission is in park, or neutral the engine idles and revs up perfectly. but as soon as its put into drive or reverse the engine instantly runs like crap, running rough, miss firing. the transmission itself is shifting fine but the engine just runs horrible untill you stop and put it in park or neutral then it acts as if nothing is wrong.

I have no engine codes showing up. I'm leaning towards this being some sort of sensor or other electrical problem since the engine works perfectly fine when not in gear and the transmission works perfectly fine. Does anyone have any ideas?

need to figure out whats wrong soon.

No, It sounds like a transmission problem. Does it happen it reverse also?

yes it happens in any gear, at idle and at speed. The transmission itself is shifting fine and I checked the fluid which was good. Not ruling out a tranny problem but it actually makes the engine miss fire and run poorly, I wouldnt think a tranny problem could do that especially when the car isnt driving? when idling in drive every once in a while itll pick up and run smooth for a few seconds and then go back to missing and running rough.

Wait, so you mean that once you start moving, it runs fine and ONLY runs bad in gear at idle?

no it runs like crap driving as well...

Most common with igniton misfires with the civics is distributor due to the coil breaking down under load Replace the distributor.

Because you have an automatic, anytime you put the car into gear, there will be some load on the engine. If something has broken in the transmission it could cause excessive load on the engine causing it to strain harder to turn the shaft.

Are you sure that it's misfiring. The shaking would be expected if there is a broken component in the transmission.