Rough idle

Like I have menitioned before in another post I have bought this vehicle at 165k and it was serviced and taken care of very well. The owner said and showed reciepts of all the pipping for the ventilation on the intake (plastic hoses running everywhere) that he had replaced. I did a tune up on the ignition (spark plugs [NGK's], wires, cap and rotor [borge werner]) and it got better but it still seems to jump back and forth between 400-600 rpms. I know that's still to low average should be atleast 700.

Thank you

Tim

It's likely your Throttle Position Sensor or Idle Air Control Valve. Run a bottle of Techron FI cleaner in your tank before you do anything else to clean your injectors, Then remove and clean the throttle body.