I have a 98 sonoma with the 4.3 V6 and I need to know how to check the coil pack. It threw a po 300 code and I took it in to be checked and was told that all electrical parts have checked out and the only thing that would cause it is the timing chain. I had the timing chain replaced and the cam sensor and it fixed about 70% of the problem. The only other things that are left are the fuel injectors, coil or egr valve from what I have found out. It has new plugs, wires, fuel filter and pcv valve. So far none of this has helped much. It has the edi (enhanced distributor ignition) and I need to know how to check it. Any help is appreciated. Thanks.