Volvo Repair: idle problem, coolant temperature sensor, volvo 240 gl

Question
hi i own a 89 volvo 240 gl.it has 200,000 miles on it but overall runs good.now heres the problem....when u start it up and its been sitting awhile it will sometimes idle rough and as soon as u put in drive or reverse it will stall.sometimes u have to repeat this 3 or 4 times the problem clears up.ill try reveving it when i put it into drive but it will still stall?i recently had the trottle clean and serviced at a volvo dealership and the plugs and wires look new.any help will be apreciated  thank you.

Answer
it could be a problem with carbon build upon the intake valves,possibly a problem with the engine coolant temperature sensor when it is cold.the idels speed motor may also not be operating properly when cold.it would need to be looked at for a proper diagnosis.whcih will not be easy to determine without changing parts and trying to see what fixes it since the problem only lasts a short time when cold.