Without seeing and hearing what its doing, I have no idea how to answer that. There's obviously a reason its acting strange. Either there is binding or maladjustment in the throttle linkage or carburetor itself, or there is a problem with the servo. Best thing to do is have it running and look at it and listen to it. sometimes you just have to mess with it as there's a lot of other variables that can come into play if the mechanicals all check out.