2000 civic ex y8 will not go over 3000rpm/30mph

Hey all. So my civic wont go over 3000 rpm/30mph it just shudders when I hit that… its in limp mode I suppose. It started when I heard and exhaust pressure sounding leak like a loud salt/pepper shaker coming from around the exhaust manifold to the downpipe area/cat…the engine runs very sluggish. So I took the pipes apart, took the cat out and looked through with light and I could see the light on the other end, everything looked intact with the cat as I thought that was the problem possibly being clogged. I bought a new flex exhaust donut gasket where the downpipe meets the cat and that stopped the loud leak finally. But now the car doesnt go over the 3000rpm/30mph. Before I got the new gasket and sealed the leak in the exhaust the car would go above 3000+rpm and 60mph like normal but the car would be very sluggish. I do have a CEL light on and I got the codes using the paperclip method. The codes are 41 and 65….now my primary o2 sensor wire I noticed has been dragging on the axle and has worn wire and frayed it open so I dont know if this would be causing the limp mode or what. I hooked up a vacuum gauge and the car does have great vacuum. I have installed NGK disbributor wires and spark plugs about 5 months ago also. Car has 214k miles by the way. (never have replaced o2’s) Anyone ever have this problem? Where do I go from here. I really need to get this fixed as it is my only daily driving car. Thanks!