Renault Clio cutting out / now non starter

i bought this car in october, used it for a few weeks, then it wouldnt start. I rewired the fuel pump relay which enabled the car to start again. then it cut out at junctions and hunted for air, although no air leaks. we have replaced the injector, (single point), throttle body, engine coolant temp. sensor,had the ecu reprogrammed and eventually rewired the engine bay as all the symptons pointed towards a wiring problem. However the starter motor now does not engage, all the dash lights apart from the battery one light up with the ignition on. it has had diagnostics tests for the cutting out problem but no definite cause was found. any help would be useful, thanks in advance.