148k miles, the car is idling erratic from normal, but consistent.
Comes to a stop and it revs up to about 1750 for a short time and then
drops down to about 900, rough idle, check engine light.
I checked the vacuum pressure by tee'ing in the vacuum line between
the PCV valve and the throttle body, the reading on the guage came in
at 15 PSI @1000 RPMs, but not sure what it should be.
I looked in the haynes and chilton manuals but could not find any
manifold pressure spec listed. Does anyone what the vacuum should be
at 1000 RPMs for this car?
I can hear a hissing sound near the firewall, but so far have not been
able to find an open vacuum line. It might be coming from inside the
air bypass valve, not sure, maybe need a stethoscope. I tried
listening to egr valve with a spare vacuum line, but did not hear any
Any ideas, TPS, EGR, air bypass solenoid, O2? Getting a KOEO 41.