When spark plugs in a vehicle go bad the vehicle may have rough idle, hard starting, stalling, loss of engine power and poor acceleration.
Your engine requires a good spark to ignite the fuel in the cylinder and when your spark plugs go bad they cannot produce enough spark to ignite the fuel properly and perform the combustion in the engine.
Spark Plugs typically last 100,000 to 150,000 miles before going bad and needing replaced.
If you're noticing a loss of engine power, increased fuel consumption, poor acceleration, engine hesitation, sputtering, backfiring engine stalling, rough idle etc then it's likely your spark plugs need replaced especially if they have not been replaced in 100,000 miles.