[V8] I was only gone for two weeks...

[Ed Kellock]

and I came home with two V8's to repair.
 
The 1990 developed a misfire... er "it runs rough at lights".  So I told her
just take the black 93, no biggie, I'll fix your car when I get home.
 
A week later, the morning I was leaving for the 3-day drive home, I get a
panicked call that the black car won't stay running. It runs really rough,
is putting out a lot of "smoke" out the back and will die off idle.
Sweeeet!  So I told her to drive the 1990 since I had at least a clue what
was wrong with it.
 
Get home and find cheap distributor cap #2 also broke in the same exact
place and manner as cheap distributor cap #1.  No more cheap distributor
caps for me.  In each case, I replaced the Bosch part that was previously
removed and it runs like a charm.
 
On to the black 93.  I suspected the ECU temp sensor was not quite right and
had already ordered and received a new one before I left.  I did a quick
visual to make sure it wasn't something obvious.  I started it and it
definitely seemed like it was running rich.  So I replaced the sensor and it
seemed fine when I started, but didn't drive it, afterward.
 
A day or two later, I take it for a drive to do errands and it has a big BOG
off idle.  I thought it might be relearning the mixture.  Not.  I unplugged
the new ecu temp sensor, no difference.  I unplugged the OXS and it was
reduced but still present.  Duh, let's pull codes.  00553 Mass Air Sensor.
Cleared it and same thing.  Took it out and hit it with mass air sensor
cleaner, cleaned the contacts on the connector, no change.  
 
So it looks like I need a Mass Airflow Sensor.  I have a parts car, so I'll
go grab the one from that and do some parts swapping.  
 
How often do these things fail?  Are there any red herrings that might throw
00553?  Was it pure coincidence or is the some way the failed ecu temp
sensor and rich running could have hosed the Mass Airflow sensor?
 
TIA
 
Ed