2003 Vauxhall Astra Car not Revving

have the car plugged into a diagnostic computer to check for fault codes stored on the cars PCM (computer) .. it could be in limp mode or a throttle position sensor fault

ok thanks will do that.

I asked few garages most saying air flow mass sensor or electrical fault, because also the exhaust back box is broken and requires a new one or either weilding.
one mechanic told me its most probably cam sensor as these are common faults in astra's and i think he is correct, it may well be that.

He told me to disconnect the air flow pipe and then start and rev car which i did, but noticed underneath air flow pipe there was a switch disconnected which i think leads to camshaft. i connected that back and started car. at first it would not start but eventually did and started revving fine but then just cut out.

so i disconnected that again and then same thing, car starts but does not rev past 2000

I need to know the fault codes from the vehicle ! .. we could be replacing parts without reason and at great expense before stumbling on the cause of the fault ! .. there are a lot of reasons the car will go into limp mode .. the codes will pinpoint the cause !!