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@garment : The relay & CIS brain only applies to the later models with lambda.
15.4 at WOT is too lean, and you need to take care of this running lean at WOT will give detonation.
Your engine (and wallet) won't like it. You should be between 12.5 and 13.5 at WOT.
Before playing with the mixture settings, make sure you don't have any vacuum leaks. Does your idle change when you open the oil filler cap ? If it does, that's already a good sign.
The mixture screw is only one part of the equation.
The warm control pressure (-> WUR) is the other one. Get a CIS pressure gauge, and measure all your pressures.
Make sure they're within specs, especially the warm control pressure.
Since your engine is lean, your control pressure must be on the high side.
If your pressures are OK, check again for vacuum leaks or cracked airbox.
If your WUR has a vacuum port on the side, make sure it's plumbed properly (check that you have vacuum on the hose at idle).
The vacuum actually makes it leaner (higher control pressure), and so when the vacuum goes away at full throttle, the engine runs richer. So if you have a vacuum, you can try to plug the hose and run without it. Cruise should be richer. WOT should not change much.
I wouldn't worry too much about not having the right WUR. Ideally, you want the exact WUR your system was designed to work with.
But all they do is go from one pressure (low @cold) to another (higher @warm) in a certain time, and eventually you can have that extra vacuum hose to lean the low / mid range a bit.
So you should be able to tune any WUR to work decently on your engine.
The cold pressure and transition time to the warm pressure are not that important, as long as the engine starts runs OK at cold, it's good enough. It's just a transition state, it doesn't have to be perfect.
The important part is the warm pressure, where your engine will operate most of the time. So get a good warm control pressure and then fine-tune your mixture screw so that you get good readings both at idle (13.5 ~ 14.7) and WOT (12.0 ~ 13.5).
Then adjust the cold pressure if needed so that the car starts OK when cold.
There are a few threads that explain how to tune the WUR by pressing in or out the large "plugs". Some sockets and a vice can do the job.
The adjustable WUR only adjusts the cold pressure, which isn't that important to me, but it's still nice to have, so that once you've tuned your warm pressure you can easily fine tune the cold pressure.
While you're working on your WUR, clean the fuel ports with compressed air, there's a little screen that can be clogged, and when clogged it will make the engine run lean.
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