I have a 2001 Ford F-150 4.2L 6 cylinder. About 2 weeks ago, while driving, the truck seemed a little sluggish. Like it was lagging or having a hard time accelerating and started idling very rough. A few times it stalled. Hard time starting the engine. Cranks a few times before finally turning over. I noticed a decrease in gas mileage and once or twice you would get a whiff of gas. I put in some Lucas Injector cleaner and changed the spark plugs. It seemed to help slightly. I tried testing the coil pack with a OHM meter. One set of towers tested slightly lower on the primary. I tested the secondary, tower with tower, and the results were fine. How can I confirm it is the coil pack? Could it be something else like the injectors?