i have a 92 Ford F-150 5.0L. i have replaced spark plugs. and spark plug wires. also the fuel pump and distributor cap. the engine shakes and leaks oil at the dipstick and into the air filter. i know that the 8th cylinder is dead. it gets oil on the spark plug and the ignition tip is black. how do i fix the cylinder?

 

It depends on what is causing the cylinder to be dead. It could be a warped head, bad valve, bad valve seal, head gasket, bad piston rings, etc., etc., etc.

You will need to determine what is causing it first.