Running rich, high idle, hesitation… I searched everywhere and tried everything

[Sinisa]

Hello everybody!I bought recently ‘92 200SX CA18DET and thanks to you I solved many problems, but this one I cant As you can see I have very common problem but I still cant find the solution.My engine is running very rich, idle about 1200, hesitate and have wall at 4000 rpm in third gear. (manual transmission).When I start the engine, it idle just fine (about 800 rpm), and after 2-3 minutes it goes to 1200 rpm and stays there. (it should be opposite!!) And if I start the engine and rev it up to 1500 when the engine is cold , it still goes and stay at 1200. And whenever it idles below 1000 rpm and I push the acceleration pedal it begins to idle at 1200.The other problem is hesitation at 2500 rpm and wall at 4000 in third gear. I think that my problems are related…

Thinks I have done:Changed fuel injectors, fuel and air filter.Cleaned MAF (it was very dirty)Checked for vacuum leaksRechecked for vacuum leaksReplaced all vacuum hoses (to be on the safe side, because this looks like vacuum leak )Checked every single valve and sensor to see are they in factory spec. (everything OK)Checked grounding (less then 0.5 ohm) and put 4 ground kits (to be on the safe side again)ECU gives me 55 code…

Things I have not done yet:Checked fuel pressure and timing because I don’t have tools for that.

When I try to set idle speed and disconnect AAC, and using idle adjustment screw set idle to 600 rpm and then connect AAC, idle goes to 1200 rpm. It don’t increase for 50 rpm! It increase for 600 rpm! Is my AAC valve bad? It gives me 9,9 ohm. I did not clean it yet because I want to know is there any other reason for that behavior?I just cant set idle speed!!Could bad timing do this? Car have past about 95 000 km and right now have very bad gas mileage

Thank you all for reading, I hope you could understand my bad English

Best regards!Sinisa