Weird Acceleration high Rev

See if I can explain this so it doesn't sound crazy, but I've noticed lately, when starting the truck after it's been sitting for a while, I'd say at least 8 hrs. Or so, when accelerating the truck revs high and shifts hard into 2nd. Also, when accelerating once I've reached the desired speed limit, in this case 35mph leaving my neighborhood, while trying to hold the speed at 35 the truck begins to Rev, rpms bounce between 1k and 2k. But...as soon as I release the accelerator and let the rpms fall below 1k then re-accelerate, it stops. And then usually doesn't do it again the rest of the day. Its so weird. Running a pedal commander and already replaced the MAF sensor. Any ideas what could be causing this? Or has anyone else dealt with anything like this?

 

I have a pedal commander and have never had any problems with it. That being said, have you tried turning it off or removing it to see if the problem remains? I would definitely start there.

 

I you tried to see if it happens if you let the truck warm up first? Transmissions like the fluid to be warm before operating. Its why the transmission actually has a warmer on it that brings hot coolant to it.

 

I installed the pedal commander after this problem started in hopes it would help. Usually if I start it up in the driveway about 10 mins before I leave it typically runs fine. It's pretty much from a cold start and go that it happens. My concern now though is, it happened to me today on the highway going 70. It reved and bounced rpms, same thing, released accelerator then reaccerlated and it smoothed out and didn't do it again. No codes have been thrown yet either.

 

Have you ever done any transmission service on your truck? Almost sounds like you might be slightly low on fluid.

 

Solid question, a 2016 is at the very least due for a drain and fill.

 

No I haven't, im due for an oil change, guess I can do the tranny flush as well

 

Dont do a flush. Never recommend especially from one of those quick lube spots. Just a drain and fill of 4 quarts, the procedure is pretty simple once you've learned it. Im sure there are YouTube tutorials and definitely threads on here on how to do it. The @Genuine Cooling Systems tutorial also documents in there installation video but I can upload the Toyota manual to do it if you are handy and want to do it yourself. Its basically level the truck, pull the fill plug, pull the drain plug, pump in 4 qts and then let the truck warm up to 99°F-111°F,(assuming its a 5.7) if you have a OBDII tool it makes it very easy but there is also a procedure you can do with the shifter that makes the truck tell you when its at the correct temp, then while the truck is running you pull the drain plug and if nothing comes out add more, if any comes out, let it slow to a trickle then install the drain plug. You can do this procedure multiple times in order to exchange more fluid if it looks bad when you drained it. If you want to, but unnecessary and not recommend if you live anywhere that they salt, you can remove the pan and get more fluid out that way and replace the filter. If you've never removed the pan and its anywhere near salt though, the bolts for the pan are notorious for snapping, I broke one myself and replaced them all with stainless.

 

I'm handy, but not quite that handy im not familiar with Toyota compared to Ford or chevy. I bought this truck used about 8 months ago, before I was always a Ford guy.