I got my 4.6 thunderbird not to long ago the odometer broke at 284,000 miles so its probably somewhere in the 300,00's it was owned by an old veteran who bought it new a long time ago and sold it to me for 800 bucks. it is immaculate on the interior and exterior. but engine wise it had oil and oil filter changes done but never had spark plugs or spark plug wires done and the oil filter put on was the wrong size. so when I bought it it was running on 5-6 cylinders I replaced the wires and spark plugs, changed the oil and oil filter and it now runs on all 8. It runs super smooth and idles well it has no engine warning light I used my code checker and its not throwing any codes. and gets great gas mileage but when put the hammer down it seems slower than I expected. like it wont even squeal the tires while my friends bone stock automatic v6 1997 ford explorer squeals the tires and feels like it launches harder. what could be the cause of this? Maybe the super long gearing bogs it down? I know that its no sports car but I would think it should be able to beat out a lower horse power heavier ford explorer.