Hello, for the last month or so I have ben experiencing this issue with my volvo S40

it is a 2003 volvo S40 1.9l turbo with about 108k miles on the odometer
It has trouble staying on after a cold start and at stop signs. I always have to keep a foot slightly on the throttle. im getting check engine code P0507, goes off sometimes but back on after driving for a little while
When i start the car in the morning or after it has been sitting a while it starts right up but dies after a second or two.
Of course feathering the throttle at startup and at stops I can keep it running but of course the second i let go of the gas completely it dies when at stops, and if not it has very low idle and dies after a few seconds eventually. :x
After the car drives for a few minutes it helps to not die as easy

I have already tried to fix this issue by doing the following things:
Replaced the battery
Replaced spark plugs and coils
Cleaned throttle body with carb cleaner
Cleaned IAC valve with throttle cleaner
checked for vaccuum leaks (found none)

3 weeks ago I also replaced the FPR (Fuel Pressure Regulator) it commonly has issues with this model, Before replacing the FPR it had much more difficulty starting and even hesitated at stop signs and lights, etc. After replacing it it alleviated most of the starting issues and hesitation however I am left with P0507 and it will not go away permanently, I have used my scanner to erase it but it just comes back after driving for a few miles.

Ive seen code P0506 on it before, and if I remember correctly It has gone from p0506 to p0507 a couple of times before in the last month or two.

Any suggestions and I would really appreciate it. I do not want to take the car to the dealership. My next step may be to just replace the IAC valve :?: not sure.

 

I'd replace the IAC motor since you have both the symptoms and the trouble codes.

 

IAC (I would see about a used one from a pick your part wrecking yard) or (good chance) vacuum leak would be my guesses.