[Dark_5.0]

It takes a minute or so for the o2 sensors to get to operating temperature. When they get to temperature the ecu then starts collecting data from them, if they are faulty they can cause a serious idle surge especially on a speed density car.

last Summer my car would start up and idle perfect until the O2 sensors warmed up and kicked in, then I had a steady idle surge.

I replaced them both with Bosch O2 sensors costed about a $100.00
and now it idles like a dream.