JeepNeNe

Proud new owner of a 99 WJ 4.0 in February of this year. Now August.... Lol I can't seem to quiet engine tapping to point it sounds like a diesel even after warm. I have changed coil pack, plugs, map sensor and Lucas oil stabilizer. I know 4.0 have normal tapping but I was under impression it was only when cold. When I'm driving it it almost sounds like a vacuum line is off some where. Or the tapping is misleading me ears. Second issue, when Jeep is cold an/ I start it and put in reverse there is a sound like spinning gears. It only does it in reverse, stops immediately when put in park, neutral or drive. I'm replacing both ujoints this wknd to see if that stops it. Clanking when put in gear is main reason for replacement of u joints. Any advice would be greatly appreciated! Thank you in advance!