Hi everyone.
Hoping I can get some help with an issue I'm having. Thinking it's transmission issues.

Background - 2005 V8 with 175,xxx miles. Tranny fluid replaced every 80,000 miles. I tow a trailer that's approx. 6000 lbs frequently (1-2 times/wk) about 60 miles round trip, fairly flat terrain.

About 2 months ago, I noticed this problem with empty vehicle (not towing).
Whenever I come to an abrupt stop, the vehicle does not want to take off. I step on the gas, the engine RPMs do not rev up, and the vehicle struggles to take off. Pumping the gas peddle does nothing. But...when I shift from "D" to "4", it will take off and drive normally. When I shift from "4" back to "D", everything works normally. This problem does not happen every time...just once is a while. The only pattern I see is it happens more frequently when I come to an abrupt stop.

About a month ago, I was on the highway doing 65 mph, RPM was around 2K. I had to stop abruptly to avoid a drifter into my lane. Slowed down from 65 mph to about 40 quickly, then back up to 65 mph. I noticed the engine running at 3800-4000 RPMs and staying there. I drove for about 5 miles to see if the RPMs would return to normal 2K range...never did. I pulled over, shut engine off. Restart, got back on highway at 65 mph and RPM was back to normal range of 2K. It felt like transmission downshifted to 4th gear and got stuck there and was unable to upshift back to 5th gear.

Does anyone have any idea what my issue might be? Does this sound like transmission issue or some sensor issue? Time for tranny rebuild?

First thing I would check is to make sure WS fluid was used at last fluid change and that level is correct. You can use this link, as is, to check level or follow a link within it to use the official method.

I have a similar issue - no recent trans fluid change though.

3 days ago I manually shifted from "D" to "4" to kick the RPMs up as I passed a big rig on the freeway. Moved the shifter back to "D" after the pass but now it will not drop into OD as normal and my RPMs stay higher than normal.

All though my RPMs are not as high as the OPs. Normal freeway driving at 65mph usually had the RPMs around 1600 or so, not they are around 2100.

Such an odd thing. I am going to check the level of the trans and also disconnect the battery to see if a reset helps.

My 05' v6 has had some shifting issues. Sometimes it will hold 3rd for way longer than needed or is slow to OD. The torque converter almost never works. I've taken it to two dealerships, had two different toyota master techs tell me all new electronic controlled transmissions drive this way and they couldn't find any issues. Funny thing is, my 04' AWD V8 dodge durango (also much heavier) got about the same mileage as my 05 V6 toyota 4runner.

Pull codes. I bet you have a 2714 code for a bad solenoid.

If you catch it early you could save the transmission. I just replaced mine. Fingers crossed I caught it in time. It acted exactly like what the OP posted.

Good info! Thanks! I'll pull the codes and see what I have.