Hey,I gotta 04 Bonneville with 106,000 miles on it.Just this week I noticed that ONCE THE CAR GETS FULLY HOT the engine will skip a beat so to speak for a second but will keep running. As the car keeps running it does it more frequently.When it does this at idle the Rpm drop for a split second and then the engine revs itself up a little to compensate. Sometimes it will cut off but it will restart immediatly with no problem.When it does this "skip" I notice a rotten egg smell which leads me to believe the ignition system is cutting out entirely for a spilt second then cutting back in. The only thing I can think of is the ICM since it doesnt do it at all when its cold.
What I meant buy hot I just meant fully warmed up,the temp gauge stays at 200-210 and never goes over that.If im on the highway it doesnt do it,which leads me to believe that the airflow is keeping the motor cool enough for the problem not to arise.Its only during stop and go city driving or sitting at a light does it do this.
Your description sounds more like a crank sensor to me. I suppose it could be ICm, but there'* far more crank sensors that fail and in the manner you mention than ICM'*. Plus it is much cheaper since you likely won't be able to get a complete failure or much more than your current symptoms. Which we all know intermittent issues are the toughest to solve.