Pro drops RPM need some advice

I had the primary spring break on my 13 Pro. It wouldn’t get over 6700 rom when it broke. Installed a new spring, test drove. Still couldn’t get up to proper rpm. Looked through things and found hose disconnected from mag side cylinder exhaust valve. Put back on and would reach rpm. Took it out for a ride. Kept falling on its head, could get it to clean up every so often. Pulled plugs. Mag side is black and PTO side perfect. Put new plugs in. Same thing, in fact fouled a couple plugs on mag side. Pulled exhaust valve and cleaned up, nothing abnormal. Still doing the same thing, will rev up and drops to 6700 and stay there unless I flip the throttle then it comes back but falls on its head again. Got a coil ordered cause I can’t find anything that could cause this issue. Voltage regulators I know are an issue but that would effect both coils I would think. Am I missing anything that might cause this?

Fuel filter or fuel pump if the pump pulls more than 5amp with a new filter the pump is fried.

Mine was doing something similar. It was fine until it warmed up and then I couldn't pull full RPM. Turned out to be a super shiny, slick belt. Changed to my spare and was pulling hard again! Not sure if this helps you, but my symptoms were like a clutch slipping which led me to think the belt was slipping and it was. Hope this helps to either find the problem or eliminate something to help you find the problem.