I have a 1985 S-10 4X4 with a 3.4 crate motor upgrade. It has just started having ignition problems. It will drive just fine for a day or two and all of a sudden it will just quit. Its not a fuel problem Im just not getting any spark. Tried a new coil and have played with all the distributor and coil connections. Pulled a plug out and turned her over. No spark. Any ideas?