You didn't specify what you've done to try to solve the problem, but cold start issues are almost always choke related. I'd verify choke adjustment and possibly replace the choke coil.

I would NOT recommend a one-size-fits-none aftermarket carb unless you want a whole slew of new adjustment problems. The Qjet is arguably the most sophisticated 4bbl carb ever made. Since you've already said it runs fine when warm, fix the choke problem and save your money.