93 Sentra is getting a gas and oil mixture under the plugs getting them wet and won't start.

Have been working on this car for a few weeks now; 93 nissan sentra 1.6L. The
gas+oil under the plugs was the original problem. We took the plugs out and tried to
start the car a few times to shoot the gas+oil out of the cylinders. All the cylinders
would fill up again right after we were done though. So we changed the fuel pressure
regulator and they stopped filling up.
Changed the oil+filter because they were contaminated with gas.
Started it with starter fluid and the problems kept coming.
The catalytic converter was clogged and red hot so I cleaned it all out removing the
platinum and put it back in as a empty pipe.  
Now when it started cylinders 1+2 wouldn't fire and wouldn't kill the engine when i
removed the wire from the cylinder when it was running. It was misfiring and sounded
terrible but it ran.
So i thought it might be the fuel injectors. I was about to check them out today but
then there was gas+oil under the plugs again and it wouldn't start today. Took the
plugs out so the cylinders could dry, but I am lost on where to go next.
I need some help.