Ok. I haven't driven very much since draining the excess fluid out of my trans. In the last couple of times I've driven it, the shudder is back. I decided to take the level check plug out again after driving it. The fluid was much warmer to the touch than when I let the 4R idle for 20 min in my driveway and did my first trans fluid level check. This morning, out came more than another quart. Here is the total of the extra fluid that was in my trans:
Looks like my trans was overfilled by about almost 3 qt at the shop I had it serviced at (remember the pictured amount includes the 24 oz I poured in before I first let out the fluid level check plug).
A couple things I've learned:
• Idling the 4R in park for 20 min DOES NOT warm up the transmission fluid. It was much warmer after driving and working than when it was just sitting.
• This transmission shop put in way too much of a generic "global" transmission fluid. I think this is why my torque converter is slipping.
• This fluid seems to be really clean...I am wondering if they replaced ALL the fluid (and added too much while doing so) instead of just dropping the pan and replacing 3qt.
• This problem doesn't happen when I drive normally. Normal driving for me is keeping it in S4 until I hit 45mph...then I go to D.
I have no shudder or slippage when in S4...only when shifting from 3rd to 4th and 4th to 5th when in D.
• After searching the forum, it seems a lot of people have this issue and some consider it a semi-normal quirk of the 4Runner. Again it only happens to me under very light acceleration and only in D mode, not S. I almost wonder if it is the adaptive programming of the transmission working against what would be a very different shift point under less acceleration. I mean, the trans has learned that I like to keep it in 4 until 40-45 mph. When accelerating very gently in D, which I very rarely do...it wants to get to 5th gear much faster. Just thinking out loud...
At this point, I'm waiting for the Toyota dealership to call me back and let me know how they do a flush or fluid exchange for this transmission. If there are any detergents or cleaners run through the system, I'm not going to do it. But if it's a simple replace-the-old-fluid-with-new, then I think it'll be the easiest way for me to make sure that my trans is full of Toyota OEM fluid. If I still have the problem after that, I'm gonna write a nice long honest Google review of this transmission shop that screwed up.
I'll keep you all updated.