2006 Ford Taurus

I recently purchased a used 2006 Ford Taurus SE with 39000 miles three weeks ago. First there was standing water on the front passenger floor, so I took it to the dealership where purchased. As I was leaving the dealership today I noticed the rpm would go no further than 2 and the speedometer would go no further than 40 mph even though I was accelerating higher. I also noticed slight trembling especially while at a complete stop. I took it back to the dealership today and the mechanic took it for a test drive and said every thing was fine. I'm not crazy, that was not happening before they fixed the clogged air conditioning today.
December 28, 2006.

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