[scoutinkeith]

well, I don't know that much about diesels, so I can't help much with that part of it, but I have heard of puting a little ATF down the throttle body on gass engines to remove carbon buildup. I've never done it though, so you may want to talk to someone that has done it to get the details.
about the front end noise, my first guess would be the track bar(frame end uses a ball joint, those are known to wear out and cause a "clunk" sound)
to better diagnose the problem, have a friend turn the steering wheel from side to side wile you watch the front end. what you are looking for is movement in any of the joints in the steering and track bar linkage. if it's bad eanough to make a noise, you should be able to see some movement.
it also might be a good idea to check the wheel bearings and ball joints at the ends of the front axle. raise the front, and try to "wiggle" the tires. (place hands at 6 and 12 0-clock positions and try to move the tire) if there is movement, look to see where the movement is at. if the entire knuckle moves, then the ball joints are bad, if just the tire moves, then it's the wheel bearings.
hope this helps ya out some,
Keith