Loss of power...

I have a standard 95 4runner 3.0 this thing. I love I just recently did the clutch bracket and got it moving again. But this thing has like no oomph... semi trucks were faster than me lol. Then I took it to a mechanic to do the dang fuel filter because somebody rounded the flare nut and I just couldn't get it... after doing that I got a little more back. But it has good power if shifted correctly through 3rd gea . You hit 4th and it has power but you can hear it lose it too. And then 5th forget about it you switch at 50 55 and you cant get it over 60mph.. and it won't hold the speed.. it slowly dwindles down but stops around 50 or 45.. I've down the plugs and wires. No significant change. The fuel filter changed it a little bit.. I get around 135 miles per tank.. I've done 2 fuel injection things. I've been thinking of doing an oil change because it needs one so I was going to take the intake off and clean everything replace the valve covers and clean the throttle body and such. Would that help? Also its sitting at 299,446 miles. It's also straight piped.

 

I had a 95 (3.0 Auto) that had terrible and inconsistent power as well.

My issue was electrical in nature, though, as the volt meter would go haywire at times, especially at idle.
I replaced the distributor cap and it ran like new, so I'd check that if I was you.
I also bought plug wires, an air filter, and MAF cleaner, but never ended up doing those before I sold the 4R.

 

Is it going into a limp mode or throwing any codes?

 

That low of MPG suggests the truck is running really rich, right?

Maybe check O2 sensors?

 

I just checked for codes and the light just stayed on either I'm doing it wrong or there arent any codes

 

Yes it does on start up. We switched a hose that they had blocked off and it's not as rich.

 

I guess I did it wrong lol but i did it right and its constantly flashing so still no codes?