Kudos to whoever can solve this car problem (old Astra)

[XCwillo]

A mates 1990 (ish) holden astra is on its last legs but untill he gets his new ute in a few months, he needs to use it.
So him and a few of his mates where out on his property absalutely thrashing the guts out, after all this, it now stalls whenever it hits over 40 k's

But its so weird what happens :S i took it for a drive myself to test it

approaching 40k's is fine, it has a bad idle tho, timing has obviously been rooted. but when you hit just over 40's (3rd gear) it jumps around abit (the sorta jumping you get from changing to a significantly lower gear quickly) and then it dies, but the engine doesnt die straight away.

So it jumps, then you lose everything, no acceleration, even tho the gear is still engaged its like ignition has stopped, but when i go to start it back up straight after this happens, it makes the noise you get when you try starting a car thats already running. so its still running, but if you wait a few seconds you can start it again.

Clutch starting it doesnt work either, after it happened i switched into second and let out the clutch, that just slowed us down and did nothing.

So breakdown, it turns off over 40k's and jumps before this happens, it has a **** idle, clutch starting it does not work, after all this is happening and the car is just rolling, pressing the acceleration makes a small noise but barely noticiable, hard to explain, but goes no where. and at the traffic lights it will just idle lower and lower till it dies, unless you slow down long before and get the car used to the low idle

Any ideas?
I think it could be the timing, once it gets to a certain point the ignition goes bonkers and goes out of sync?