Been thru 5 starters (different brands from 2 different stores - all rebuilds) in 14 months. Car runs flawlessy with 180,000 miles but on every 3th or 4th start it starts to turn then WHAM WHAM - it's like the starter gear is hitting something. If I keep the key in start positon it will "drive" through it and come back up to speed and start after a second or so. Happens mostly when cold although occasionally it will happen even when hot.

The latest mechanic examined it and pronounced the ringgear and fly wheel flat, not out of round, solid and the gear has all the teeth with no signs of wear. He says his gut feeling is that it is an ignition thing like a backfire that is pushing back against the starter, although he says the timing is dead on. He said he's seen cars so out of time that the starter breaks. He thinks the only possible explanation is the module that advances the timing for start is malfunctioning and he didn't know how to test it.

So the question: Does any body think this is a reasonable possibility and know how to test this module - what ever it's called. Or is there something else I should be looking at? I've got about a month left on the current starter and the current store is starting to look at me funny...

Thanks in advance.