Our engineering firm has an 01 F150 (4.2L) w/48000 miles on it. Since it was purchased it spent its week days driving 30 miles to and from work, and on a construction site the entire day.

The employee that was using it isn't with the company anymore so the truck is sitting at the office. After driving it today I noticed that it's idle is really loud and there is a spark knock under heavy accelleration.

I'm thinking about doing the 60,000 mile service, myself, early due to the abuse it's seen on the job site. Should I go ahead and change the spark plugs and wires?

The only maintance it's seen in the 48,000 miles is oil/filter every 3000 miles.

Also, I have a Ford service DVD for the 03-04 models. Is there any or much of any difference between the 01 and 03 F150?