Re: taurus leaping
I had a similar problem in my 99 taurus. When the engine was cold, the rpm's fluctuated and the care seemed to jerk or leap. When the engine was warm is ran ok, but with bad gas millage. I pulled the spark plugs out and they were in horrible shape. I replaced the plugs and the car's been running like new.
I doubt with a 2005, that your spark plugs would already be bad. Go ahead an pull them and see what they look like. Also, check your plub wires and make sure they're in good shape. You might also have a problem with your distributor. Pull the cap off and make sure no 'crap' is inside. It could also be your timing or even a fuel injection/computer problem.
If I were you, I would replace the plugs (very cheap) check the wires and the distributor. If they are good, then you might want to pay the $80 bucks or so to have a diagnosis run on it. Hope this helps