First I'm going to start off and say that I've been around the block with Hondas, so don't be afraid to get technical.
I have a 95 EG sedan ex with a bone stock D16Z6 Manual trans.
The car has 262k on it and still runs awesome, but recently some mysterious problems have come up.

When I start the car and it starts to warm up my idle drops to right about 250rpms, and shutters violently. I have also noticed it is running extremely rich. No CEL's. Under acceleration there is no loss of power. No ticks or knocks either

So far I have changed/checked
TPS
Throttle body
FPR
Fuel filter
02 sensor
MAP sensor
Plugs
Wires
Distributor
IACV
FITV
Checked timing and it is spot on

And before you start bashing me for throwing parts at it, i have a complete car ive been using as a doner.

Someone please shed some light on it l, as I am completely stumped

 

Have you cleaned the IACV, replaced the PCV valve, and adjusted the idle speed.

 

Yeah I did all of that and still nothing

 

Give details. The more the better.

Does the CEL work?

 

Yeah CEL light works, i just checked it and no codes

 

Color of spark at the plugs? Bright spark at all 4 spark plugs?

Will engine start with starting fluid?

Plug wires installed in correct firing order on distributor cap?

 

Well I thought of the crazy idea for the hell of it swapping it with another P28 I had laying around, and guess what! Boom it idles and runs flawlessly again

 

LOL good. So the ECU was bad?

 

On the questionable ECU, you can pop it open and see if any components are fired or popped.

The electrolytic capacitors are known to pop after 20 years.

Sometimes it's as easy as unsoldering one component and soldering in a new one and you have yourself a good ECU again. Not always, but sometimes.

 

Haha I guess so, I tried resetting my stock one a few times but nothing, someone on the inside must of went bad

 

Is it possible some of the parts from the donor car you used could be faulty as well? Not trying to bash you, but I figure if it's likely to go out it might be smarter to just stick with new parts. My civic has been giving me problems lately too and I've been told to stick with new parts just for extra measure.

 

Interesting, mine has been doing something similar for about a year. It can drop to the low 200s when warm, sounds like crap at idle, dropped MPG down to about 24-27 from 29-31. I've cleaned the IACV and replaced the PCV too..

SO, I guess I need to look at the ECU too..