I Have A 1991 convertible 5 speed that is not running right. It will start hard by laying into the gas pedal and you have to stay on the pedal to keep it going. The plugs are new. I checked for spark on all 4 plugs and its there. I pulled the plugs out again and found that the rear rotor plugs were brown like some sort of combustion was happening but the front plugs still looked like they had never been fired. Any ideas? Is it possible I have a bad injector or an electrical problem or is the rotor fried? I dont have a compression tester but if I put my finger over the plug hole I can feel some pressure pushing back. Also I can see the apex seals through the spark plug hole so they are at least there to some degree.

 

Get a compression tester.