the best way is to use propane or carb cleaner,start the car let it idle and spray in small amounts around the intake manifold where the gaskets are if the idle changes (slows down or revs up)that is where the vacume leak is.
but you might not find one because your light only comes on when crusing under load not at idle,thats why i siggested checking the sensor.
98 svt sil/blu 3.0 oval heads full P&P, msds headers,bat kit,2,1/2exhaust 30 inch glasspack and 2 spintech mufflers
14.78@94mph
with my mechanical arm i can shift gears in less then a twentieth of a second for sale $7000
