1999 Legacy 2.2l was running pretty good.  Parked for couple days, then when starting engine stumbles along barely able to get to 1000 rpm.  Hunches were fuel or exhaust plugged.  Cleaned mass air flow sensor, no change.  Intake pipes clear.  OBD code is 0440 Evap.  Vacuum at idle is 15, drops when giving it throttle.  Lots of exhaust flow out tailpipe.  Fuel filter replaced 1500 miles ago.

If it is running, I can slowly pull the intake tubing off the throttle body slightly, then it revs better.  Let it drop to idle and it dies.  Am thinking the mass air flow sensor is bad.  Thoughts?  Thanks.

Edited October 19, 20187 yr by Ground02

check for slipped timing. I THINK you also have a lage-ish tube from the IACV to the intake - sometimes they are loose at the intake end.

code 440 could be holes in the fuel filler neck.

My thoughts are - what's the live data say? Without being able to see the sensor inputs to the ECU, we really can't help you. 

GD

Texan - I am going to have to replace a water pump that leaks when you shut down the engine anyways, that will be when I will check the timing.  Intake tubing was cobbled together by previous owner, ran better before this after I sealed up leaks.  Was thinking the 440 code was fuel filler related, but not the cause of my current situation. 

GD - tools I have right now for gathering data are Torque Pro for Android connecting to OBDLink LX adapter over bluetooth.  What software would gather the data you are looking for?  I have a windows 10 laptop with bluetooth.  Or point me to where I can upgrade my knowledge.  I'd rather learn about a smart diagnosis than just throwing expensive parts at the problem.

Well I was not cleaning the MAF correctly.  I thought you just spray it into the MAF housing engine off.  I removed it from the housing and tried to clean it.  Engine ran well for 10 seconds, then died.  Something had changed, so  replaced MAF for a whopping $36 and it ran well.  Case closed.