Revs with clutch pulled

Welcome to the forum. Glad you've found us.
You didn't say what engine or carburetor you have so this advice might not help.

Your symptoms are consistant with an air (vacuum) leak somewhere in the intake circuit or crankshaft seals. When you have a leak the engine gets more air and leans the mixture causing a high idle, loss of power and other unpleasant conditions.

Start where the carburetor attaches to the intake manifold moving on to the intake manifold gasket at the cylinder. There are two crankshaft seals. One behind the small primary gear on the right side, one behind the magneto rotor (magnet) on the left.

Of course this is if you have a Chinese 2 stroke engine. It's always better if you give us some details when asking questions so we know what we're dealing with. Hope this gets you started in the right direction.

Tom