factory recomends every 30,000 miles or 60,000 if you are running platinum plugs.
its a Nissan for starters but it could be the plug wires or the plugs or the distributor
Replace it
Your spark plug manufacturer would recommend your replacement schedule.
unscrew them
On a 19 year old vehicle I would suspect you have a vacuum hose that is leaking. Replace all under hood vacuum hoses.
normally around 100K
This is for the '05 Frontier, but should be what you're looking for. http://www.clubfrontier.org/forums/f23/how-change-spark-plugs-2005-gen-2-frontier-40507/
They are under the ignition coils. 5/8" socket and 8 " extension.
After 105,000 miles. Nissan Maxima spark plugs are platinum-tipped and lasts for many years.
To change the spark plugs on a 2010 Nissan Frontier with a 2.5L engine, first, ensure the engine is cool and disconnect the negative battery terminal. Remove the engine cover if applicable, then locate the spark plugs and disconnect the ignition coils by pulling off the connectors and unscrewing the coils. Use a spark plug socket to carefully remove the old spark plugs and replace them with new ones, ensuring they are properly gapped. Finally, reattach the ignition coils, connectors, and the engine cover, then reconnect the battery.
No. Points went out decades ago.
To change the spark plugs on a 2008 Nissan Frontier 4x4 with a 4.0 V6 engine, first, ensure the engine is cool and disconnect the negative battery terminal. Remove the engine cover if applicable, then carefully disconnect the ignition coils by unclipping and unscrewing them. Use a spark plug socket to remove the old spark plugs, replace them with new ones, and torque them to the manufacturer's specifications. Finally, reassemble the ignition coils and engine cover, and reconnect the battery.