Well, it's an 11 year old car now and there's probably a few items may need attention beyond your basic oil changes. If it is still running the factory plugs/wires/fuel/air filter/brake fluid/coolant, you might as well take the time over a weekend and check/replace all of the above IMHO.
A lot of people forget about brake fluid and coolant, but these are often overlooked.
Brake fluid can absorb water over time. If your coolant is "dirty" green, it's probably overdue for a coolant drain/refill - changing it every 3 years or so goes a long ways.
Invest in a factory service manual (Helm is pretty good) and dig in.
for the plugs i used motorcraft original ones, because the heads are really deep on the 96 - 98 cobra i had to use a tool designed to get motorbike spark plugs out. take the plastic covers off of the plug wires using a small spanner, mine were hand tight so easy to whip off, take the plug wires out and get the spark plug wrench down there. mine were the stock ones and were easy enough to take out, even after 80k