test and replace the distributor

I know that this answer is a bit late, but it may help somebody.My daughter has had the same problem twice in three years. Her early 1999 Mazda 626 stalling, first time on a roundabout and then, on two days ago, at traffic lights.The first time, after a very costly distributer 'rebuild' the engine still mis-fired and stalled. Only when I replaced the distributer-cap was the fault cured. This time, I fitted another cap straight away. £25 (about $38)I put it down to the engine-heat weakening the spring in the top of the cap. The fella in the parts store did state that he is careful where he sources parts from, as some makerss use inferior materials. This confirms the earlier comment. He also mentioned that he had had to replace 3 d-caps in 5 years on his Mercedes, at £80 ($120) a time! Ted Kelly. U.K.