poor performance 2500 - 3500 rpm

Ihave a 98 Eclipse with a turbo. Between 2500 - 3500 rpm performance is poor. During acceleration it hesitates and surges. Seems like it is running rich because if you back off the gas, you get a surge of power. Problem is worse with colder weather and problem almost goes away with 75F to 80F air temps. I suspect one of the many temperature sensors, but which one?

Could be a vac leak somewhere. Small, but big enough to give a problem.

how do your spark plugs look?

how do your spark plugs look? QFT (Quoted for truth)