I've got a 2006 4.6 STX 4x4 with 178,000 miles.No oil leaks,no smoke,clean coolant. I'm no mechanical genius. This thing is not running great. It's got an intermittant ticking noise and has a slight miss st idle. This truck was a lease fleet vehicle and was apparently well maintained,although I can't get maintenance records. I've put about 40,000 miles on it with oil changes every 3500 miles. What can I do to get this truck running a little better and keep it on the road for another 100,000 miles? Also,are there any mods anyone can suggest to give this truck a little more juice? Thanks.

I'd replace the spark plugs for a start. Perhaps a compression test while the plugs are out. And if it still misses at idle, I would check for vacuum leaks. A tuner would perk up the performance noticeably.