Before you decide to pursue lemon status, you should check the lemon laws according to your state (there should be info in your owners manual too). It's pretty common that for lemon law to apply that the issue must be recurring, it must have taken long periods to repair each time and usually it must also make the vehicle unsafe to drive. There are many qualifiers that vary from state to state but characteristic noise isn't one of them. If the dealers mechanic states the problem is nothing more than noisy injectors - but those injectors are functioning properly - I doubt you'll be able to get it qualified. Same with the mechanical issues you've described, grunting/grinding/vibrating etc while driving at a lower speed. If it truly is a characteristic of the vehicle and doesn't impact drive ability ... you likely won't get the results you're hoping for.
Be aware that once you state to your dealership that you're trying to get the vehicle classified as a lemon, it's very likely that you're going to alienate not only that dealer but you'll not be making friends at any dealer. Everything you come in to have done under warranty will be chalked up to a disgruntled owner and every repair could easily become a confrontation. You'd be better off trying to work with the service manager to determine exactly what the problem is. If the service manager says it's a normal noise, ask them to grab the keys to several other jeeps of the same model/year with the same drive train. Compare the noise in yours to those - if yours is significantly louder then see if you can get him to agree that it's extreme then get him to agree to a time to have it serviced. On the other hand, if the noise from these other vehicles is similar to yours - then it becomes a very unfortunate situation where you're just overly sensitive to that noise. And as I said above, characteristic noise isn't a problem for the dealer or the manufacturer.
Good luck on a good solution to this - whether you get it repaired or replaced.