You dug this out of 2006,... but I would suggest you re-gear, does your V6 5vz-fe have a gear ratio of 4.10, 4.30, or 4.56, mine has and e-locker with 4.30 gear ratio and it rolls on 33" x 12.5" fine, lots of huge hills on the Hwy in my area, not great but better than a 22RE, so I suggest you re-gear or determine the power loss, 33" is maxing out even 4.30

 

My 3L towed only a wee better than the 22RE but since I only tow occasionally its a moot point. My vehicles are commuters only 90% of the time

 

mine has the 4:10 ratio. it’s just utterly gutless I feel like I have a cat problem but i dont know

 

You just answered your own question, you cannot run 33" tires on 4.10 Ratio because your vehicle will be very sluggish and shift gears all the time, 4.30 ratio is pushing it on 33" x12" tires and it would be advised to run 4.56 ratio. It's not the Cat, its your tire size/gear ratio.

And Jazz1 shouldn't drive a 4R with tongue weight like that on coil springs, the unbalanced load although on tandem axle is not safe even with electric brakes operating, I pull with my 4Runner and I would be very concerned operating that on any road especially with the 3.0L

 

the thing is I had 30s on it before and it was just about as gutless maybe not as bad up hills, my brothers got a 97 runner and it’s got 32” mud tires and it halls a** compared to mine

 

Changing to bigger tires is like re-gearing, 30" to 33" is a big difference, 4.10 ratio and 33" tire will cause the EXACT issue you describe, perhaps your friends 97' has a different gear ratio, did you check, does it have the e-locker? and your measuring performance by the butt-o-meter?.., perhaps you have low compression did you check, I can suggest you clean your MAF, TB, tighten up your shift cable, insure you have the correct plugs, no brake dragging, but in the end, you cannot run 33" tires with 4.10 ratio because it feels gutless, you need to re-gear, you are not the first to put 33" tires on a 4.10 ratio and say hey my truck is slow and I need to re-gear or put smaller tires on, I run 32" on my other 99' 4R with 4.30 ratio and it is noticeable reduction in performance from factory tire size, I run 33" on a 97' with 4.30 ratio and it is tolerable and the absolute max tire size for that ratio.

 

3.4 engine is reliable and durable, but: " the power of a 4 cyl and mileage of a v-8 ! " (not my original).

 

So it turns out my brothers 4Runner has 4:10s and so I’m thinking there’s something definitely wrong. It drives like a completely different truck. There wouldn’t be a difference between 32” mud tires and 33” a/t would there?. I’m just at a stand still now. And I already know what you guys are thinking you can’t put 33s and expect there to be no power loss. Just would like some ideas

Its Got
new spark plugs
new fuel pump/filter
Cai
new timing belt

 

Nah, that's the 3.0, 3.4 isn't bad with a 5 spd. Auto trans does make it feel weak, night and day vs std trans. That and the tire size are probably your problems. Or you could do a leak down test, or compression test although that's much less useful. If you never adjusted your valves odds are that you burned one or ten and will have to pull the heads and do a valve job.