Have you tried a 2.4ghz system yet? Is the antenna or any of the wires running across the aluminum frame? Have you tried new servos? One of the wires could be pinched somewhere, inspect everything! Have you tried a rechargeable pack?

Sounds like you should use some brake parts cleaner on your one way bearing in the roto start and definitely pre heat the engine with a hair dryer to help loosen up a new engine before starting.