95 Tacoma overheating, need help with troubleshooting

V6 5VZ-FE Engine
friend bought with 244 miles, automatic 4wd, slightly overheats in long hills and heat….
discovered that engine was recently rebuilt with new heads, gaskets, water pump, timing belt, valve covers, etc.
Radiator looks recent….
friend replaced cooling fan clutch and thermostat, didn't help
i have checked compression, 205-215, excellent, spark plugs has right color, ran engine even without thermostat, it still going towards red in hills….
truck seems to have little less of power than other tacomas….
WHAT YOU WILL CHECK NEXT ?
Thanks

 

Was the radiator flushed with the water pump or just drained?
With the age and mileage the radiator may be partially clogged, and may need to be replaced.

 

It sounds like a clogged radiator if it's overheating at a good speed.

 

Thank you for advise, and, you were right !
Here is short video:
http://youtu.be/Yhrjm4NrSOU
Thank you.
Have a nice day.