I replaced every intake gasket (MAHLE) with torque specs according to the Haynes manual and little changed, engine is a little smoother when it's starting to lug but still atrocious fuel consumption, still have 172 176 411 codes. triple checked every vacuum line and now when I pull one off the manifold the RPM drops (before it increased). Tested plugging each vacuum line except for the fuel pressure regulator and none of them affect the idle. I am now wondering if my idle is actually high, the tach reads 1200 but the tach is also broken (wont read above 1500 when interior cold, stuck exactly on 2200 when interior warm). There is definitely substantial rev hang, it will go up to what sounds like 2500ish rpm while changing gears and when sitting at a stoplight but goes back to the typical idle when the throttle is stabbed sharply. (it has always done this). what's weird is that the throttle plate itself is not sticking, I opened the hood while the idle was stuck high and the plate was bottomed out on its stop screw. unplugging the IAC does not lower the idle either, whether it is idling high or how it usually does. This truck is turning into quite the enigma. my current plan is to make sure the exhaust manifolds are sealed (I hear a tick from bank 2) and replace the 02 sensors (yes I know its a joke about "mechanics" just throwing 02 sensors at the codes). What else could be happening? When I got the truck it had a MAF code which went away when I cleaned it (truck was run with a hole in the intake pipe by previous owner).
sorry for restarting old thread
