Hello everyone I have a 04 TB Ext with a 5.3L V-8. Love the truck except for one issue: It has a misfire when cold or hot. CEL code PO300. Which is a random mis-fire. Truck has almost 90,000 miles and has been maintained religiously. Has new A/C delco plugs and wires,new intake manifold gasket, new fuel filter and air filter. I have cleaned the throttle body and did a BG fuel system service. Replaced ignition parts twice in last three months. Also replaced two coils even though they specd out fine. I am at wits end. Any help would be appreciated. Thanks in advance!