Hi,

You have been working over this engine pretty good. I have been away for awhile.
Traveled to a ship reunion, In Dayton Ohio. A lot of inventions started there for cars!

I think I remember that you have had several posts on several issues.
Glad to hear that you have ironed out a lot of them.

I think I remember that you were addressing fuel and spark issues heavily before.
Don’t remember if you changed the CPS?
Don’t remember if you worked over the ignition relay module behind the battery?
It’s a heat related fault device!

Art is starting with a heat related possibility because of your Texas location, I imagine.
If things can happen, they are always bigger in Texas! That’s their slogan!

I think he is going with engine heat rising up under the fuel rail and the hood getting hot from a larger than normal sun there in Texas! (:)
Art is thinking that the rail is “Consequently” getting baked.
On the 1993 the fuel line does serpentine around a bit before going into the rail.
Just as an experiment, you might try wrapping up the rail or just the extra length of line with aluminum foil. Do it just a little loosely or several turns to allow an air gap between the rail and the foil. This will deflect infrared rays from both directions from getting into the fuel rail.

So I want to ask, is this happening only during the daytime when the engine is hot?
Just a thought?
If you park over a hot asphalt parking space this might account for more of a fuel issue, IF, it heats up the pump or filter a bunch!
All of the above is a big O guess!

There are three things things that let pressure go, if they are weak.
A fuel pump check valve.
A weeping fuel pressure regulator.
One of four injectors, as this car does not have a cold start injector.
If you have one leaking injector it would would run rough until it cleared that cylinder.
Only trouble is, all of the above would have it do the same thing, almost all the time.


Excessive air is also a fuel related issue. Both ideas are lean related.
Another thing that I do not know if you addressed or not, is the flap in the air cleaner.
It stops heat from coming over from the exhaust manifold. That thing needs to be disabled into a permanent closed position! If always open it plays heck with the AMM.
If that thing is holding open it will create a leaner than normal fuel mixture upon startup as heated air is less dense with oxygen.
HOT air rises or actually can push heavier cooler air down with expansion. Lighter air will be drawn, along a pipe first, because it weighs less. It takes less inertia or force to get it moving first and therefore empties the top part of the pipe first.
This can cause a stalling situation “temporarily” for the lack of cooler incoming air being instantly being moved.
A crack or tiny hole in the accordion tube behind the AMM can cause stalling situations while idling at a stop light. If bad enough, it might be twisting open when the transmission engages on the weak mounts.
Is the air cleaners “ proper filter” in there and is it clean?
Believe it or not, the air filter acts as a minor baffle to stabilize air fluctuations from a moving car and from the engines operational changes.

But the whole “Drive gear thing” with the transmission and loading up the engine makes me think the IAC is sluggish in responding.
I have no idea how things being hotter could be affecting that component.

I would concentrate on it losing spark first or the IAC being slow, since you can stall it with the transmission twisting things under the hood as it goes into drive.
Heat and your actions are being claimed as consistent.

Phil