my 90 celica gt is running a little rough, i replaced the spark plugs and wires connecting to my cap. It is running a little bit better now but still seems like its firing on 3 cylinders. I'm leaking a little bit of oil into my distributor but that is common for this type of set up. I was wondering if that is the problem or do you think i need a new distributor? I was told to just replace the gasket for the distributor. What do you guys think?