Want to improve the performance of my 06 Taco

Hey, I was wondering if anyone had some tips for me on the best ways to improve the performance and the longevity of my Taco. It's an 06 SR5 5-speed manual with a 2.7L i4, it has around 425k on the engine and it's feeling really sluggish. I got it not that long ago, the previous owner took very good care of it, regular oil changes and all that. A notable (possible) issue I've noticed is that at around 3k rpm when I'm in second and (also) third gear I can hear the engine(?) cranking quite a bit. As of right now I can't think of other problems (other than it's being sluggish now and again), so I'll updare if I think of any others.
Thanks for any help

 

At that mileage I'd have a compression test done to see if poor piston seal is causing a drop in power. If your compression and valvetrain is still good, for more power you need more fuel and air, so anything that can improve those metrics will net you an increase in power. If your fuel system is still working well, increasing the amount of air to the engine should result in the ECU giving you more gas and more power. This is the theory behind removing the charcoal filter on the intake or switching to a high-flow CAI.

Changing to an LCE exhaust manifold has been shown to give a mild increase in hp, but a very useful increase in low rpm torque. This won't make it a sports car, but it should make it feel like its struggling less.