YES.....and the Admin- Ang as well.

OP- Where I was going. If this only happens when it is cold, engine has been off for at least "x amount of time" and there is no issue with the FITV and it runs fine once warm...Could, could be a leaking head gasket allowing coolant to get into the cyl's....until it burns off, bad idle. That is where I was going with the compression and block test. When you pull the plugs for the compression test, please note how they look.....I hope I am wrong but need to test to be sure.

 

It does idle fine when its warmed up but only in N and P. If I throw it into Drive or Reverse then the car idle dips VERY low and acts as though its going to die, and it does die sometimes. This problem, I am pretty sure, has everything to do with the topic of this post.

Do you know why my car idles so badly in gear?

 

I just recently changed my spark plugs and they had a coating of grey / white on the firing tips... This problem that really did not start occurring until I poured SeaFoam into the PCV vacuum pipe.

After I did that it started having this problem at cold start-up. (Note that while I was burning the Seafoam off I noticed the seafoam smoke coming from a large hole in my flex pipe. Could a hole in the flex pipe do this?)

In the Haynes manual it is listed in the Troubleshooting section that a faulty emissions system could a car to stall out. Things like the EGR valve also could cause this. The thing about it is that I am getting no CEL's, which makes me think that I could have faulty wiring.

 

The 91 accord will not throw a code for EGR flow (plugged EGR ports). If this has never been done on your car, then I would clean the EGR ports on the intake manifold. In the common DIY thread on top of this forum, there should be a link to cleaning them for the 90-93 accords. Search the web for another set of good instructions.

EGR port cleaning should help the car run better.

I am not sure if it will help the idle problem at startup.

Your 91 has 3 air bypass valves. The IACV, FITV, and the air boost valve. You will have to block the port with your finger on the throttle body for the FITV on a cold start to see if this is the source of your idle problem. The air boost valve has a vacuum line going to it that you will have to undo and plug the port.

The other option is to spray carb cleaner around the intake to see if the idle will change for an air leak. The ericthecarguy site has a video on how to find intake leaks with this method.

It would also be a good idea to inspect all the vacuum hoses for signs of deterioration.

 

I am having a similar issue and was wondering if maybe it could be valve related when they are cold and just need to be adjusted. It only happens to me when the automatic choke has stopped working but the engine isn't completely warmed up usually about 3 minutes after starting. Once it is warm it runs perfect and is still getting good mileage. Mine is a 99 EX manual with the 4 cyl.