I have a 1988 Cherokee with the 4.0L I6. to make this short my oil pressure is at 80 and my 6th cylinder is not firing any suggestions. I have already checked spark plugs and have already checked distributor and they are fine.

 

I would confirm the oil pressure with a mechanical gauge. I suspect its a fault oil pressure switch.

As for the missing cylinder, have you determined if you spark in that cylinder and if the fuel injector is firing for #6? If you have a snappy blue spark and if your fuel injector is firing, then it would probably be time to check the compression.