I had a similar problem. It was primarily because the throttle cable was too tight. The slack in the throttle cable changes as the engine heats up, so when it gets hot the cable does not allow it to return.
Not sure if it helped, but I also made a small wooden block with a groove in it, and attached it where the cable makes a sharp bend going into the cable adjuster stop at the engine. That sharp bend bothered me, and the block just gives it strain relief so that it doesn't kink.
Don't overtorque that cable adjuster. Its easy to break. You can guess why I know.
Not sure if it helped, but I also made a small wooden block with a groove in it, and attached it where the cable makes a sharp bend going into the cable adjuster stop at the engine. That sharp bend bothered me, and the block just gives it strain relief so that it doesn't kink.
Don't overtorque that cable adjuster. Its easy to break. You can guess why I know.