Air Fuel Meter Idle Mixture screw

[Porsche 935]

Long story short. Many years ago I bought 84 911 which needed so much work previous owner decided to sell because fixing everything was going to cost as much as he paid for car. I started with adding air fuel meter. Found aftermarket chip and car running richer than gauge could register. Changed that to a sw chip. Fuel regulator bad, replaced. Fuel pump weak, replaced that, checked tank and replaced fuel filter. Flow to rails good now. Car was so lean i had to turn air fuel meter wheel out 7 notches (yes, I know you shouldn't do that) but engine would have melted. Fixed intermittent air leak in hose going to brakes. New head temp sensor, original was one wire. Starting the car would still show no cold enrichment and go into the mid to high 15's during warm up. Replaced injectors this weekend with a set of five o racing units that are suppose to be a good replacement. Car started and finally saw good cold enrichment , but after warm up was a bit too rich everywhere. Turned air fuel wheel back towards factory setting by 3 notches. Can definately go more but here is my issue, idle becomes too lean. the adjusting screw is working but bottoms out. Anyone know what it is pushing on or adjusting in the air meter. Idle is at 14.5, tip in high 12's but wot sees high 10's and settles in at 11.7. Too rich in my opinion. Car has been nightmare to sort out after so much neglect but may also be trying to achieve the unachieveable due to the high mileage(218,000). Any input from here is appreciated.