Idle goes up and down rich then lean

[Mr666]

The car is a Nissan GTR R32 , it ran perfectly before engine was out and rebuilt

Here is the problem, the car starts up for the first time of any day with a slightly fast idle around 1150 rpm and smooth, as it warms up the idle starts to get faster as the fuel air ratio goes down (11:1) and then the fuel air ratio goes really lean around (20.6:1) and then the engine slows down. So the fuel air ratio displayed on the wide band goes up and down with the rpm surging up and then down: Here is the back ground: The engine was taken out for major overhaul and everything was touched. Throttle bodies were match bored and no the shafts are not leaking air as I tested for that. The throttle stops were all backed off so the butterfly’s seat on the bores in an attempt to get the idle down. Yes I know this is bad but I am trouble shooting. The Air regulator for idle control is electrically disconnected in an attempt to get the idle down. The AAC idle control for the A/C is electrically disconnected in an attempt to get the idle down. There is now no fuel tank canister and the air bleed for it is blocked at the front throttle body. There are no Narrow band O2 sensors in the pipes but I never had them in before the engine was out and I already programmed around their absence. There is a wide band but not hooked into the computer. The MAF’s were working fine before I took the engine out but you never know? I have Nistune and can program it but I have gone through it line by line changing values and getting no fix to the problem. Personally I think it is the fuel air ratio that is changing for some reason (going rich then lean) and I am at a loss as to what it is causing it ? I do have some Z32 MAF’s that I could switch in but I have to wait for wiring plugs and silicone hoses to arrive to try that idea out. Is there anyone out there who had something similar happen to them cause this is getting to me? I can change the latency and multiplier to get smooth idle before it warms up but then the idle starts going up and down up and down rich then lean.

Matt is there anything you can suggest ?

[bachig24u]

what work was done to the engine and intake piping?

[Matt]

Take a log of the issue in stream mode over the warm up process. As the temperature warms up, the amount of injection from the ECU should reduce

Apart from that there is no reason for the ECU to behave differently otherwise. One would think that perhaps an airleak somewhere in the throttle would cause extra airflow to be pulled in where not normally expected at idle

Also checking the base timing when warmed up is what the FSM states

[supersayianjim]

hey op. when you close the throttle plate while driving does the afr's get really rich??