Best advice take it to a garage and let them do it. If you choose to do it yourself go by the parts store first and pick up an intake manifold gasket set. In order to get to the rear spark plugs you need to remove the upper half of the intake manifold as well as the EGR valve. Once that is off the plugs are right there. While you have everything else off it wouldn't hurt to invest in some new plug wires, rotor button and cap. This is not a hard job it just takes a while and is frustrating.
4 spark plugs
I assume most of the V6 Stratus' are similar, but this information comes from my experience with a 1996 ES model.The three plugs on the front bank of the engine should be obvious by following the spark plug wires; they're set deep into the cylinder head cover. The rear three can only be accessed by removing the intake manifold.
It should fit, but the wiring, and computers will be wrong.
modual
four, as it is a four cylinder engine with one spark plug per cylinder.
platinum plugs 75,000 miles. resistor plugs 30,000.
You do not need to gap double ground spark plugs. Just put them in right out of the box, but note how they are gapped. As the plugs wear out, the gap increases, so when you notice the gap increasing, change the plugs.
Disconnect the battery, remove the spark plug cables and covers, and remove the old spark plugs. Next, put in the new spark plugs, reconnect the spark plug cables and covers, and reconnect the battery.
There is an article with video on how to change spark plugs at ; http://www.carbasics.co.uk Look in their 'how to' section.
they are dropped down inside the valve cover. pull the plug wires and use a plug socket and extension to reach them.
Check the catalist maybe old, replace the air filter make a change of spark plugs and wires. put some additive to the gasoline a proof if you feel power the gasoline is cheap.
1.13 mm or .050 That's the gap my plugs are running at on my '95 Zetec (Motorcraft plugs)