rough running from cold start vs warm start

[Eoth]

Hoping someone knows what is going on.... When I start up and drive from "cold start" the engine runs a bit rough and I notice I am missing some horses.... It will continue to run this way no matter what the engine temp gets up to and how long I drive. However, if I shut it off for a bit (like running into a store) and restart it warm, then engine runs great (smooth and power is where it should be).
I the engine is a explorer 5.0 with Fitech FI and HEI (Dragonfire) ignition.
Any idea what is going on?

 

[blubuckaroo]

Maybe a faulty heating element in the exhaust oxygen sensor.

 

[Eoth]

Interesting.... Didn't know there was a heating element in there. I believe I have a spare floating around... Worth a try!