Hey guys I need some help figuring out a couple of problems with my 2001 Dodge Dakota. It is a 5 speed with a 3.9L V6 68K miles, all stock except a K&N air filter. Last year I noticed that my MPG dropped suddently. I live in a pretty moutainous region and I was averaging 19-21 MPG depending on if I drove any highway miles. Anyways my MPG dropped to about 16. So I changed the plugs, plug wires, cap and rotor. Seemed to help a little, but my engine began to idle rough. So I rechecked the plugs and wires and I had a bad plug wire, so I replaced them with a different set and replaced the plugs again and it seemed to help the idle some but not completly. MPG picked up to about 17. Well just recently I began to notice that when I start the truck up after it has been sitting for a while there is a knocking or I guess more of a ticking like sound when you first start it up and then it quiets down after the idle begins to slow down. I let my dad listen to it and he kinda thinks it sounds like a lifter or possibly the valve train needs adjusted. So I decided to put Seafoam in my oil to see if it was a sticky lifter it that would help, and so far it has helped some, but not completely but my MPG picked up to about 18, still not what I was at. Could you guys please help me out! Also something else I noticed and I don't know if it has anything to do with it, but I had my air intake box disconnected from the throttle body a while back and noticed that there was some oil in the tube that connects the throttle body to the air intake box. I really don't know if this is bad of if it is supposed to be like that. One other thing I have noticed is that when the truck is under hard acceleration, I hear a pinging noise which I assume is the spark plugs arcing. I use 87 octane gas which is what is recommened for the truck. If you guys could help me get this straightened out I would greatly appreciate it! Thanks guys and sorry for the lenghty post!