Assuming it's a petrol it could be any of the following:-
fuel pump/relay, coil pack, spark plugs/leads,injectors, idle control valve, crankshaft sensor, camshaft sensor, ECU or wiring, the coil pack is one of the most common faults or the idle valve if it's cutting out at low engine rev's
It would be worth taking it to an independant garage or tyre & exhaust place and get the fault codes in the ECU this will cost around £30 but it might save money in pointing out the faulty item rather than just changing items at random
nc, June 2009
