200sx tune up

[svtcobra03]

alright i just bought a 1998 nissan 200sx, its been sitting for about a year or so. the owner would drive it every other week. recently i've changeing the oil, air filter and fuel filter. The previous owner has had the car for about 4 years not sure as of what "maintenance" the car has recieved. it currently has 142k on the odometer. these cars are suppose to get around 35 mpg average, but i tripped the last tank and it averaged around 24 mpg. whats the next step!?!? TIA

[91CoupeMike]

Change the plugs. Go from there. NGK

If it has wires or cap and rotor change them too.

Also seafoam the combustion chamber through a vacuum line and run some b12 through the tank. do this on the old plugs and change them after you seafoam it.