We have a 99 Ram with a 5.2. It has always knocked, since about 25k miles. We have replaced the PCV twice, and had the ignition software updated. After getting the first pcv replaced, it worked fine for a month or two, then started knocking again. We ahd the siftware updated, and it was fine for a few months. After that, it pinged like hell, almost constantly. We then had the PCV and ignition replaced again, and it seems OK after 2 months. There is still an occasional loud "TICK" from the engine under heavy load. Should we look at the EGR system, or what else?