Timing Trouble.

Definetly check and set the timing first. I've had them that are hard to see the timing indicator also but you just have to do it. Timing affects carb. settings so it has to be right to even adjust the carb. correctly. It sounds like an adjustment of the carb. idle mixture screws are in order too. How old is the carb? Does the accelerator pump give a good shot when you open the throttle?