I built a 383 stroker chevy motor,It has a holley stealthram,comp280xfi cam 9 8 to 1 compression,24lbinjecters.The problem im having is 1 of my plugs#4 is burning funny it is a wet black color.compression is 175 the heads are edelbrock E-tec 200 they have about 3to 4000 miles. My 7 other cylinders are burning a light grey,Can a bad fuel injecter be the problem?