I have an 03 Bonneville SLE that is stalling at idle. Sometimes the car will start right back up, but other times it won't unless it sits for a few minutes. When it doesn't start, I rev the engine, getting the RPM's up but then they immediately drop back down and it stalls. I am not getting any check engine codes.
My transmission fluid is currently a light/medium shade of brown. The car has about 109,500 miles on it. I have been told that I should not have it flushed, but rather drained and filled as well as having the filter replaced. My mechanic estimates this will cost $180. Do these sound reasonable?