Transmission issues need advice.

Hi all I’m hoping I’m not the only one on here who have experience this issue. So iv got a 10 inch lift and 37s… the last owner of unknown origins probably drove the truck hard. Dirty oil is the only indicator I have besides the tranny issues. So when I’m doing freeway speeds 60to 75 when the tranny downshifts to get up to speed the truck kind of shutters. I feel like it also hangs out in 4th all the time. Every time I shift it to sport mode just to see what gear it’s in it’s in 4th. Iv only really experienced this at freeway speeds. Has any one had this issues too. The truck is a 4x4 too. Iv read that it could be the torque converter. But I’m wondering if it could be the solenoids? The truck is a 2008



update. Did a drain and fill. Well I took the pan off as well. Ever magnet had some metal particles on it some more than others with two magnets completely covered. Truck seemed to be great for a while but still shudders at high speed. It seems to shift through gears just fine I’m thinking it’s the torque converter for sure. Any help would be great.

 

What year? 2007 and 08 had faulty/weak spring dampners in the torque converter causing shutter issues along with flex lock causing it to overheat. But most were at a 45 mph before a shift. Running 37's...is it re-geared to say 5.29? The 37 tires with stock 4.30 gears will make hard to stay in 6th with constant down shifts. Its normal when in drive and shifting to sport it goes to 4th gear.
Easiest would be a drain/fill of atf which could help. Especially if a lot of clutch material gunking up the solenoids.

 

Agree with @Mdl start with a drain and fill, get the dirty fluid out. I've read somewhere if it's pretty dark, change it out every 1k miles. If it's dark, but you see some cherry red, then drain and fill every oil change. Till you get to 16 quarts, then every 30k after that.

 

Where would I find 5.9 gears? I’m pretty sure it’s stock and it is a 2008

 

Toyota WS fluid gets dark quickly. Adding some lubeguard platinum to the ATF oil can help with shudder. But you need to address the gearing if you’re gonna run 37s and a 10” lift. Both create more strain and it is certainly compounded at highway speeds.