Thanks for the suggestion but it is not engine icing in this case. You can tell it is not engine icing because the thrust becomes stuck at one setting. If it was engine icing I should be able to reduce thrust.

I do my test flights from my local airport which is here in Florida, the weather has been in the 80's (in degrees Fahrenheit) and above. I can never reach cruise altitude and it happens just after crossing 10,000 feet. Also notice that I said thrust cannot be reduced. If it was icing I should be able to reduce thrust. The thrust becomes stuck at whatever setting I have when I press CTRL + E to restore power. For example if I have 75% thrust it becomes stuck there. That is definitely not icing.