Hauling, turn it off. Otherwise you can leave it on.
Myself, I like to leave it off unless I'm going above 50. Less shifting and more responsive throttle. The "low power" thing is because of 2 things. Overdrive is a 0.69:1 ratio gear. Pretty nutless (pardon my french). Your transmission also has what's called a "lockup torque converter". Basically the tq converter is a fluid clutch that makes a solid connection with no slip in Overdrive. It also does it in 3rd. Kinda resists a bit of throttle input though it will unlock and operate as it does in lower gears. Does this for several reasons:
1. Longevity- in high gears, overdrive and it's 0.69:1 ratio for example, fluid flow through the converter is very low. Low fluid flow=low cooling ability. Low cooling ability=increased fluid degradation=shorter longevity. I can personally attest to this having run 5 years with no lockup, dual coolers and a gauge and yet still having burnt fluid within 10k miles
2. Mileage- pretty simple concept really. solid connection=less slippage=less engine input to maintain cruising speeds. Engine doesn't have to work as hard. Again, on mine personally, I got my trans swapped out completely (various reasons, old one only operational issue was the lack of lockup) and mileage went from 12ish cruising at 60 to 15.9 at 65. 15 solid at 70, 14.5 at 75. It's wonderful. I feel like I'm driving a v8 prius compared to before.
Any way you can better describe your lack of power? When does it feel weak? Speed?
Also I apologize for late reply, I haven't been around in a while
