Ok heres the deal. Over about the past 2 years my explorer has been getting crappy gas milage (13mpg), and has also been knocking. Recently it has started hesitating. I just did the plug and wires today, we'll see how they work out. I also have a new fuel filter for it. Ive also re-torqued the intake, and it did good for awhile. Ive had to up the fuel to premium so it wouldnt knock. The car has 195,000 miles on it, with about 37,000 on the engine, and a few hundred on my manual tranny that just went south Anyway, can I get some opinions? Maybe I should pick up a spark tester? When I pulled the plugs the chart in the haynes manual said the plugs looked normal/rich condition...... Thanks for the help guys.