I sounds like your problem lies in you house ducting. There is always resistance to air from ducting. The longer the duct, the greater the resistance. The thinner the ducting, the greater the resistance. The more bends and elbows, the greater the airflow resistance. Sometimes people have to run 6" pipe for long distances, and there are dryer duct booster blowers that you can buy and install on long duct runs.
How long is your exhaust, how big is the ducting, and how many bends do you have in it? I'm not sure how to figure out if it is too long, but the installation manual should give you some numbers.
If your element gets "RED RED" hot it usually means you don't have enough airflow. When the airflow is good, it's color will be, as you said, "PINK BLACK" My guess is you have RED RED when the duct is hooked up, and PINK BLACK when it is not hooked up.
It doesn't appear the moisture control board has anything to do with running the heater.