So I have a 2000 Dakota 3.9L that has 145000 miles on her. A year or so ago it started smoking just a bit on start up. Since then it has gotten worse at burning oil on start up and I am adding about 3/4 quarts of oil every 1000-1500 miles. I have also noticed a pinging/clacking noise when I accelerate hard but goes away at normal driving. Again, it only smokes on start up. Could this be a bad plenum gasket or valve seals? Or a combination of both. Thanks in advanced.....