My ETS Off Light is on (no check engine light) on my 99 Z24. It doesn't happen right away, I drive about 67 miles one way to and from work. After driving for about an hour that light comes on. The car starts jerking (ex. like if you were to put you car in reverse and back up and while backing up pop it into drive from reverse, some cars jump or jerk you when you do that). It started last year around Sept 2004 and I had my transmission fluid changed, no more problems all winter until memorial day 2005. I feel it may have something to do with the heat. I have no problem in morning time at all, just in the evening. Does anyone know what might be causing this to happen?