c70 probs

[viggen]

C70 T5 1998 49,000 miles one owner good history, problem i have is starting from cold instant, starting from hot instant, but if i turn it off and try and re start within 5 seconds when hot it splutters into life.
Also i have once had this happen when racing round an island it lost all power no lights came on but it was as if the fuel had been cut, the tank had around 5 gallons in it. are the two related???

things i have done so far
plugs
leads
cap and arm
fuel filter
cam sensor
cleaned throttle and idle out
tried mass and ecu changes
this car is cable throttle any help appreciated.

[Liddo]

It SOUNDS like a bad earth somewhere. Id get an auto electrician to check it out.

But then, Im no expert ;)