Toyota Repair: Corolla running on three cylinders, toyota corolla, platinum plugs

Question
Dear Mr. Ritter, I have a 1996 Toyota Corolla that began running on three cylinders. My first guess was that I might have a dead plug so I bought four new platinum plugs and began to change them one at a time. Three of the old plugs were a light grey, almost white, but the fourth one was dark brown. The brown plug was NOT wet or fouled in any way. After putting in the new plugs the car continued to run on three cylinders. I pulled the plug on the dead cylinder and it was dry. I then wound the motor over and there is plenty of spark to that plug and to the other three. It seems as though it is not getting gas to the problem cylinder. Do you have any suggestions ? Thank you.

Answer
The first thing that should be done is to check the engine's compression, all cylinders should be around 160 psi, if one of the cylinder reads a lot lower then there is a compression leak in that cylinder. If the compression readings are good then I would suspect that one of the injectors is not working and should be replaced