I'm having an issue like this too, Have you removed all of the sparkplugs and tried to turn over?
Here is what I’m seeing.
1. The engine turn overfreely without the sparkplugs.
2. When I put onesparkplug in, the engine will bog down and pause. For example, With all of thesparkplugs removed. Then put a sparkplug in #1 cylinder while on TDC then crankthe engine, it will bog at #1 cylinder. It will do this on all cylinders.
3. with all of the sparkplugs init will barely turn over.