Hunting\Stalling\Overheating\ECU Light.


Hello All.
I can see various posts about similar problems but ive got a slight variation on a theme.....Anyone got any ideas?

hijet 1999 1300.

Runs fine cold. In fact runs a treat.
Once it gets up to temperature, it starts to hunt and if i press the throttle pedal down to fast, the engine stalls and then instantly re fires and repeats, leaving me bunny hopping along the road. Steady off on the throttle and its back to ok again. At the same time as the stalls, the yellow ECU light comes on but is off for all the rest of the time.

Also it appears to overheat on the temp gauge, but only ever gets to about 3/4, no more, never boils and doesnt feel hot to me inside the engine bay.

I took it to the Diahatsu garage who charged me a fortune to plug into the computer and tell me there were no errors in the ECU. Im not even convinced this model has a socket to downloads the logs?

The garage told me it needs a new throttle body. Not 100% convinced.
Also they checked the coolant system for pressure and changed the filler cap as it wasnt sealing. There doesnt appear to be any coolant loss.

They say they "tested" the temperature sensor but didnt replace it.

Ive got a new sensor to fit tonight so we'll see on that, but i suspect it wont make any difference.

Symptoms again.
Fine at cold. Once up to temperature, hunts, appears to overheat (not convinced) and stalls\re-fires\ECU light comes on at stall.

Any ideas anyone? Im really struggling with this one.