Well she does puff a bit of smoke on startup but it clears up within a minute or two. Lack of power? Well compared to my new truck or a big block, yes, but I would say its typical of the first of the 7.3's, boost really comes on about 2650, down low its not really there, but I am pretty sure mine ran about the same. I will try to pull some codes this weekend and see what that holds. We park it in my shop every night and havent seen a leak one as of yet, so I guess that is a good thing, although a leaky tank would be an easier problem to diagnose for sure. I had heard that a MAP sensor could do that to mileage, ever try that?