Are you sure you need the cold start valve? There are other things that can cause hard start,but cold start valve should not cause the rough running after start up. Cold start valve works only when you are cranking the motor over and not once it has started.The thermo time switch can cause the cold start valve to not work. Rough running could be a vacuum leak, EGR valve that is stuck partially open or poor fuel delivery,(ie: low fuel pressure or volume). You can have an ignition problem for the rough running too. I recommend having it thoroughly checked out before you start swapping parts, because they are not cheap and you cannot return electrical or special order parts. Good luck.