My 2002 jeep 4.0 158,000+ miles is pinging more then it use to. Would go as far as saying excessive. I think the issue maybe in the last year wife now works in town 1 mile round trip. I do take it for run once a week on a 50 mile trip but speed is not over 50. I think I am getting carbon buildup. Tried gumout regane no help. Years ago in my repair shop i would do slow slow water drip down the carburetor (remember them) and it would work. The jeep has port injection i believe. Any issues dripping down the Throttle Body. Any better ideas?? Thank you