The problem is that the engine won't continue to run for more than a few moments without serious backfire. It is firing on all cylinders at once, repeatedly - even allowing for the wasted spark system. Have replaced both crank and camshaft sensors with new ones. Cam alignment is spot on, done using the appropriate tools. My understanding is that the crankshaft sensor will tell 'when' to fire spark. the camshaft sensor telling the computer 'which' cylinders to fire. To my mind, it is the computer that should be collating all this sensor information and making mechanical sense of it: but it is not, I think, doing this at all. I cannot see what else the problem may be as there is nothing else to determine 'when' and 'where' the spark should be sent. The coil packs seem perfectly fine.
I do not have a decent workshop manual (a book one) and am still trying to seek one out - have been for past few months!