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Apologies if this is frequent enough a topic to be annoying, but I can't find the previous site's search refinements

2009 Base model I-4, 2WD, 215k miles

While descending the Rocky Mountains, alone on a rocky mountain road at ~20-30mph, the engine started stuttering and the oil light started flickering. I thought I punctured the oil pan, being a little too free and easy up there, and thoughts turned very dark. Then it stopped doing that and continued to run as it had for the previous 5 years: just fine.
Later in the day, it started dying when I came to a stop. Not every time at first, but I did have to start watching the dash for lights and sudden drops in RPM while coming to a stop. Very frustrating, as I had to quickly flick the shifter to N, make sure restarting while in a turn didn't lock the steering, and then flick it back into D.

Before I left for the trip I had a mechanic give her a once-over and he said the battery was testing weak and recommended replacement. It's a Bosch and not too old, but I had noticed it being a little weak on starting. After the long drive though, it was cranking like new, so I assumed that since I work barely a mile away it just wasn't getting the longer recharge/run time it needed. (BTW, I would totally bike or walk but the road that connects home to work is very unsafe, with no shoulder.)
It also starting making a sound like metal rattling when after the engine catches, and at points when the car is moving and under load but before downshifting. This isn't as loud outside the car (tested by echo off nearby objects) as it is inside the car.

After reading the site, I decided to clean the throttle body. It worked fantastically. Seemingly gained 30hp, ran like a top, and didn't know my idle speed had been low for years. Thought for sure that was it, but then it started stalling again when coming to a stop.
I cleaned it a second time yesterday, yet the intermittent stalling when coming to a stop at a certain pace remains. Otherwise, car runs absolutely beautifully.

Here are some details about when it stalls:
• Only stalls/flickers oil light after the engine has warmed and whatever adjustments the computer makes after starting have been performed. That means if it dies and I restart, the time it takes to start acting up again is a couple minutes, or a stop sign/light down the road.
• Only stalls/flickers oil light during a normal stopping procedure. As in, the quicker and more abrupt the stopping, the more likely it will die. If I creep down to a slow roll into the stop, the downshifting and idle will save it from completely dying. But if it disengages from the driveline (if that is accurate) because of a quicker stop, it's like there isn't enough momentum in the engine alone to keep it running. I tried manually downshifting to keep the motor engaged, but unless it's slow enough to put it in L, it doesn't make a difference.
• Once it dies, it restarts on one or two cranks. No electrical power issue is suspected, except maybe a loose ground wire. Also, the new alternator is less than a year old.

Some other things I've tried:
• Seafoam fuel treatment before a 60 mile round trip yesterday. Read about possible dirty injectors. The engine runs fantastically. More power than it's ever had, on tap, throttle pedal just needs to be feathered now. Mileage is much improved (by the dash calculator, but everything points to the same in reality.) Transmission shifts smoother than ever since I'm not mashing the pedal too.
• Reset codes by disconnecting battery. Once the computer learns what it needs, it returns to running just fine.

Some things I've considered from reading and thinking about it:
• Perhaps the transmission and engine aren't connected properly due to failing motor mounts. This makes sense to me because it seems during a more abrupt stop that engine would rock slightly and decouple from the transmission. But, on a gentler stop it wouldn't and everything would stay as it should. Motor mount replacement is not a task I'll be able to perform.
• Battery ground loose. Makes sense because of the same as above. Too much movement, temporary disconnection. Will check later today, but just discovered my multimeter's guts have been dissolved by an exploded battery in it, though.
• Something more in-depth was damaged while things were out of whack from a dirty throttle. Just read about the VVTi "death rattle" on the V6's but not sure that would be it on an I-4, who knows. Any other mechanical problems know to arise from this problem?

In conclusion (for now), I've read enough to know that this is a topic that requires a lot of try-this-and-see, i.e. something that can drain someone's money by leaving it to a mechanic to guess. So, I may as well exhaust all my DIY options first. I'm mechanically inclined, and have the normal household/garage tools of a handy dad, but throttle work is about where I draw the line. It is definitely a problem I need to keep at, daily, until it's fixed, but I live in North Texas and it's August so outside labor is extremely restricted. Lots of qualifiers, but basically I'm willing to try a bunch of intermediate level stuff before I take it to the shop. All suggestions, help, and conversation appreciated.
 

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Seems like you have a couple problems such as the oil light coming on and a weak battery. You should address those two things first.
 

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I have a 2008 Rav4 Limited with the 4cyl engine. I was having many of the same symptoms you have discussed, especially the more abrupt the stop, the worse the idle drop. I have a Bluetooth OBDII reader and was watching the Throttle Position Sensor on the throttle body. At idle, it would not stay stable. I too had cleaned the TB, seemed to work a little better, but not much. I went ahead and replaced the throttle body from an online parts place (Toyota wanted over $500) and it has made a world of difference. Since the TPS is attached to the TB, you have to buy the whole body, Even though the problem stems from TPS. Hope this helps.
 

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Unless I missed it in your post , but did you check for codes? Disconnecting the battery will help get rid of codes , but they will come back if the problem is still there. Sounds like your engine is in good state of tune, not sure what else you could try. Might be worthwhile to take it to a seasoned mechanic for a diagnostic check, then you can decide if you can do the repair yourself.
 
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