The 4.0 isn't a huge bump in power when you factor in weight. The curb weight of 3rd gens (4x4) is roughly ~3950 lbs, where 4th gens are ~4300 lbs and 5th gens weigh up to ~4800 lbs. That's a weight increase of 9% and 21.5%. I test drove a 2018 4Runner and was very underwhelmed as far as the engine goes. Even my wife said it was a slug trying to get on the freeway and she doesn't drive my 4Runner half as hard as I do.
The 4th Gens with the V8 do have a noticeable amount of power though. Lots of low-end torque where you will notice it.
For the OP, here's a few things you can try:
- Do the "deckplate" or "elbow removal" mod. Gains are around 5 HP on an N/A engine
- If you have a 96-99, remove the slack in the throttle cable.
- Make sure your spark plugs & wires are in good shape
- Switch to sythetic fluids in the transmission and engine
- Install a lightweight flywheel (doesn't add HP but reduces rotational mass)
- If you are a glutton for punishment, headers increase HP but more so with a Supercharger on it
You can find a used supercharger in the $1000 range even today. If it's a black 2nd gen, you can rebuilt it for as little as $150 and nothing else is needed. That will give you the most bang for your buck. Fuel mods are not necessary for the supercharger, only if you want to make more HP.
