You might want to familiarize yourself with Wiki SHO. There's a huge amount of info there. For instance:
Tach dropping to zero points to the camshaft sensor. Run your finger along the bottom of it to see if there's any oil there. Parts I use:
Camshaft Sensor (Duralast) F134 Autozone
Cam seal (National) 1213N O'Reilly
I've had at least 22 cases where the spark plugs have been completely immersed in oil, but the car has always run fine. Doesn't do the wires any good, though.
Observe that the secondary butterfly valve tabs are down engine off, meaning that the secondaries are open. Start the engine to make sure they are now closed with the tabs up top.
Bogging down under hard acceleration indicates a vacuum leak or dirty MAF. I've had several cases where this happened. Car runs fine under gentle acceleration each time.
I just took the old cam sensor out and it's full of oil so I guess I'll be replacing the the cam seal now. Is it right inside where the sensor sits?