It could be the warm up reg needing fuel pressure setting, that's what it is on mine as its too rich, but start with the thermostat and go from there. Its more likely to be fuel setup than the stat I'd have thought, as the head will still get warm and unchoke the wur through heatsoak..however the engine could still be at the wrong temp for the fuel mix its being supplied hence the kangarooing..it could also be isv issues if its cutting out and idling rough, do a bit of searching and youl find loads on setting it up, and what to test etc if the stat doesn't help that much..