There is a write up somewhere on this site, I forget where.
But, short of it is, there is a plate cover on the side of the throttle body, it's sealed on with silicone, so you just dig out the silicone, carefully pry off the plate.
After seeing mine, I knew exactly why it does what it does, the plug for the air mass sensor goes in right to the side of this plate, and directly under this plate, you see where the plugs pins solder to wires that then go to the circuit board, which is the board for the mass sensor wire/wires buried deeper in the throttle body.
The point where the wires solder to the pins of the plug internally, are chronic for being dry soldered, and I suspect this point also sees some vibration, so when you look at them under slight magnification, you can see where the wires in the plug pins have fractured.
You have to know what your looking at to understand, that this then creates fluctuating resistance through those pins, which on a lot of things is not so much an issue...
But, a air mass sensor, calculates air density by the passing of air across a heated wire, how that wire cools is how the car knows how much air your engine is getting, fed back as very fine resistance measurements to the ecu, the very finely and minutely cracked solder joints will expand and contract with heat and more vibration, creating all sorts of random readings, making the car do all sorts of weird things that mimic other problems.
I'm in a rambling mood sorry, you can solder in place, that's how I did mine, but I'm a fair to above average solderer, I made sure I totally re-flowed my joints to a nice shiny wet joint that I knew fully penetrated the join, but I will admit it's a prick of a job to do in place, if your less lazy than me, it's likely easier to pull off the throttle body and do it on a bench, then you can also be sure you did a good repair on the dry joints.
Should really find and post the pics of mine, I took some close ups that show just how dry the joints were, with the fractured wires in the middle of the solder blob...
