Power issues between 3rd and 4th gear

Hello all,

My Tundra developed an issue recently and I have been unable to determine the cause or find any forums with information on it. Bare with me as I try to get all the info I can out in one post.

The vehicle:
2002 Tundra, v6 auto trans, 2WD approximately 56k.

The issue:
Vehicle has recently developed an issue with power at the top end of third gear. When heavily accelerating, the engine will shift properly from first through third. As the engine revs up in third at WOTor near WOT, the engine will rev but there is no transfer of power to the transmission. This begins at approximately 4k RPM/55MPH. As the engine continues to rev, the truck actually slows down. The trans will eventually shift into 4th gear as the RPMS reach the top of the gauge. On some occassions, the truck will shift into 4th gear and still have a lul in speed. Engine revs like 'normal' but there is no speed there.

If I let off the gas, the trans shifts up and grabs like normal. If I accelerate at a less intense pace, say 3/4 throttle or less, then the engine revs and trans shifts as it should. This isn't something that happens 100% of the time, its more like 75% of the time.

I've cleaned the MAF recently (the proper way, that much I know), with no change in performance.

I've read similar issues as this, except they happen off the line in first gear. So not what I'm experiencing.

Has anyone had similar experiences or know of a fix? I'm thinking possible MAF replacement (~$40) but am looking for guidance before throwing money at the truck.

Thank you in advance.

 

First off when was the transmission serviced last? Oil and filter?

 

Welcome to the fourm

 

Sounds to me like a transmission problem.

 

Thank you for the responses, and thank you for the welcome to the forum.

As for the transmission service. I have no clue when or if it was serviced. The truck is my girlfriends, it was handed down in a will about 5 years ago and honestly has probably only seen 20k since then. Not much use on this guy, spends most of it's time in our driveway. The fluid is a little dirty but still pretty vibrant red with no visible debri on the stick.

I'll look into flushing the trans fluid out. These are internal trans filters correct?

 

There is a pickup filter inside the pan. But I'd start with dropping the pan and inspect for brass debris in the fluid and other debris on the magnets. Sounds like something is slipping inside the trans.

 

Anything else done recently to the vehicle? When was the last time the timing belt was done?

Does the truck have power off the go? In gears 1-3? Or is it just 4th gear only?