So no one replied to my last thread.
I've got a 1999 Volvo S80 T6 and the only codes I can see with my scanner is for all 4 O2 Sensors.
The car requires the gas pedal to be pushed to start, and once it's running and I let off the gas it drops under 1k rpm.
About 500 rpm... gets very rough at that idle and thats on a cold start.

When warm it keeps the 500 rpm,
Why is it idling so low on a cold start it should rev up to 1200-1500 rpm

So cold and warm it idles to low, no other codes shown and I don't have DICE+VIDA

 

The O2 sensors can throw codes when they can't compensate enough for a mixture problem - but are not the cause of the problem itself. Sounds like you have a vacuum leak or a dirty/stuck idle air valve. Check all the vacuum lines and then open the intake to see if its clean or dirty. Clean with MAF cleaner...

 

Ok I cleaned my MAF I have to see how that's affected it tomorrow.

Idle air valve is apart of the throttle body and electronically controlled, But I did clean the throttle body when I had it out to change the alternator.

The vaccume lines arent like brand new condition but they seem ok, I'll try spraying some ether around them and see if I can get something to suck some in and rev up the car then I'll know the area to inspect.