How are you Phil
I bought a pioneer with plug and play wiring adaptors Get them at Frankies ,Repco ,Ashdowns ect but beware my steering wheel conts worked
with the old toyota radio but not with the new one
With all you have done maybe its a bit tight , But is the thermostat good even being new could be a dud
Waterpump check the impellor on the shaft could be slipping , You mentioned your radiator not genuine be worth checking