confusing issue 99 B16B

[obracer12]

Engine:
b16b
stage 2 cam
valves, seals, retainers
test pipe
2.5" exhaust
cap, wires, plugs replaced 3 months ago
fuel filter last year

NO CELs


Scenario: car runs fine until warmed up to op temp. after that point at low rpms the car will sputter then even out past 2.5k

I'm thinking the O2 sensor is throwing a rich condition and throwing timing until the rpms get up and the fuel curve evens out.

Thoughts?

 

[stcopley]

Ignition timing would be my guess. Sluggish acceleration until 2.5k? Happened to my z6 del Sol. Could be a few things though.

 

[obracer12]

I was thinking the following:
O2 flow is too high and it is pulling timing
The temp sensor / sending unit are going bad and running a cold curve