1994 explorer oil consumption

Hi Everyone
My 1994 Explorer has about 127,000 miles on it and runs great. I have kept it very well maintained(changing oil every 3000, filters, etc.) but recently I have noticed that it burns a quart of oil like every 300 miles or so which seems like way too much. It doesn't leak anything and isn't blowing out any purple smoke. I have noticed that there is like a black oily substance inside the exhaust pipe around the tip of it. Last year I had a problem with rocker shaft mounting bolts breaking so I had to have the rocker shafts, mounting bolts, rockers and push rods replaced. This was kind of a freak thing I'd assume. Anyway when I fire it up in the morning it usually has a faint tap in the engine but shuts up when the car is fully warm and sometimes it doesn't do it at all. I guess I should also mention that I just changed the spark plugs so maybe that will make some difference. If you are still reading this I was wondering if anybody had any insight on what could possibly be the problem.
Thanks

Try getting a leak down test done. New plugs can't get rid of an oil loss problem.

You should have examined the lifters, and cam when you did the work to the push rods, lifters, etc. The noise could be one of the lifters, but it most likely just need a valve adjustment.

Fords don't have the best bearings on the bottom end, so that might be the problem too.

I lose about a quart of oil every week or so myself. sometimes two weeks or three. i never checked the exact mileage. but your oil pan gasket could be leaking. it doesn't have to be a large enough leak that you would notice oil everywhere either. its a simple problem that is insane to fix because to get at the oil pan you have to take out your entire engine. check everyth8ing else but if you can't find it then its probably your oil pan and just keep spending that buck fifty to throw a wuart of oil into it because it would cost you a mint to fix it.

Thanks for the info guys
mike