First, the 2 sensor is probably just part of the issue as your mechanic has said. With the mileage it is time to replace as aprt of routine maintenace. It can have dramatic affects on gas mileage as well as performance.
A common source of idle issues is fuel management. If you can rule out vacuum leaks and spark plug wires, etc. Then look into is the Idle Air Control Valve, IACV, which is sometimes also referred to a the engine Load Sensor, ELS.
This is an electro-mechanical device which idles up the engine when loads such as; power steering, A/C and other accessories or situations call for it.
It can adversely affect the performance of the engine.
It is tough to diagnose problems such as these because electric/mechanical control modules feed from sensors all over the engine and accessories which makes it hard to tell if a sensor is bad, the control unit is bad, an IACV is a control unit that sometimes has integrated sensors, or if the is a problem with the Vehicle Main Computer.
SPONSORED LINKS
Monday, August 22nd, 2011 AT 5:33 AM