Please clarify my thinking
My 2.0 spider is idling really poorly, it has had a replacement MAF, which made no difference to the problem, and the idle stepper motor is functioning exactly as it should.
When the car is cold it idles just fine, if a little high, but once the car warms up the idle drops down and it splutters and coughs, occasionally cutting out when coming to a stop.
My thinking is that that the car ignores the Lambda sensor until it warms up, then as soon as it starts to use the lambda signal the idle deteriorates.
The only spanner in the works is that the engine management light never comes on; I would think that a faulty Lambda would cause a fault to be logged.
Am I talking Nonsense?
Is there any other component that could cause the idle to be rough but the car to run fine on throttle?
At the cutting edge of cocking about.