Hello all,
I have been noticing I guess what would be "slipping"
It happens around 45mph when it shifts
So the shift will begin, engine revs up for a second, I let off the gas and the then it completes the shift, and RPMs return to normal.

So question:
1) Should I do a transmission fluid flush? (Following this thread: DIY: Non-Sealed Transmission Service for 4th Gen T4R's and Prior)

2) Replace the solenoids? If so, if I do the flush in the thread mentioned above, will I have access to the solenoids to change them out?

Thank you for your input

Hello. More info might be helpful.
How many miles on your truck?
What type of service has the transmission had? Original trans fluid?

I am over 200k

I bought it used about 5 years ago....
I have done none on the truck myself.
I have no idea if any was done w/ previous owner. So I am going to assume none has been done and the fluids are original.

I had an old Silverado...and did a transmission fluid flush on it, and that made a noticeable difference in shifting
So I am thinking it might be similar for my 4Runner.

Fluid is getting old and breaking down. Do a fluid exchange now while you still have life in it. Several ways to go about it.

I did a procedure like this: https://www.youtube.com/watch?v=WngXE_7vg-Q&feature=youtu.be

It's been several years and thousand miles. I used Maxlife fluid. Shudder I had at the time went away and all has been fine since then. No I didn't open up the pan or replace the filter. There was debate on this that it's not necessary due to being a metal screen type. Like the video, I just kept repeating the process until I had fresh red fluid coming out.

Okay. I would have said try a drain and fill but maybe maybe you should consider a full fluid replacement. I'm not sure if it is warranted to replace the filter with your first attempt.

I am sure others will chime in.

Thank you gents for your input.
I will give it a go and see what happens.

You don't think the solenoid should be replaced?

I'd start with the most conservative course of action and go from there. The conventional wisdom here is a full fluid exchange - not flush. A flush uses pressure and you don't want that. There are numerous links here and I think some YT videos on doing the exchange using the cooling lines and such. I've done mine twice.

About the fluid, some people swear by Maxlife and it's cheaper than Toyota WS. Maybe it's fine, but a fluid that claims to meet the specs of many different manufacturers and transmissions seems too good to be true. This isn't like coolant, where aftermarket long-life red is specific to a range of Asian vehicles; Maxlife supposedly works for everybody. Plus, the guy in the video seems to know a thing or two about the topic and emphatically says ATF is not a one-size-fits-all proposition.

There's no maybe with WS - I know it works. Granted, my take may be different b/c I intend to drive this truck until one of us can't get out of the garage anymore. Your truck, your call, but that's my 2 cents.

Ok, I will go the route of draining and filling the fluid first.
I was going to go ahead and pay for the Toyota 00279-000T4 Automatic Transmission Fluid,
I believe this is the correct one for this 4Runner?

$50 for 192 ounces.

According to this post, that is the correct fluid IF your truck has a transmission dipstick. If there’s no transmission dipstick, it uses WS fluid. Please double-check before going ahead since the process may be different too. People say a full exchange takes varying amounts, typically always at least 12, and personal experience has been 14 quarts on my ‘07.

Also, consider ordering the fluid online from a dealer with an online parts department. Many offer significant discounts, some with free shipping (or you can pick up locally if convenient), and you’ll know for sure it’s genuine OEM fluid. Site is parts.toyota.com and be sure to check several dealers as they set their own prices.

As mentioned that maybe the correct fluid or not, you don't want to use it if it's not the correct fluid.

For us to confirm which fluid you need we need to know what year model you have and engine you have would also help!!

I do have a dipstick.
I will look around as you suggested.

It's the 4.0 L engine I have, with a dipstick.
Is there somewhere on the engine I can get the exact model?

Do you still have your owners manual? The fluid type is specified in there. At the end of the manual, in the specifications section.

Fluid type:
Toyota Genuine ATF WS

The dipstick should also say Type-IV on it.
When I did mine I changed it with Amsoil signature series ATF. Its been a few thousand miles already with no issues at all.

I will look and see
I bought it used, so it may not be with the vehicle.