engine doesn't wind down when cold

[peeeot]

I've noticed that most mornings (first start) before my car warms up, I'll accelerate as normal and when I put the clutch in the engine will continue to spin at the speed it was spinning when I started to shift (~2500rpm)as if I was keeping my foot on the accelerator. When it warms up, though, rpms will drop the moment I let off the gas and push the clutch in. Has anyone else encountered this?

I was having some serious cold start idle problems recently that were eliminated by replacing the 24x crankshaft position sensor... I'm wondering whether this other issue might pertain to the other (7x) crankshaft sensor.