I have a 2003 Lincoln that is jerking bad between gears. Hoping its not the transmission. tester said first cylinder (spark plug) as per parts store. would a bad spark plug make it jerk between gears.

Well, if it is every gear change I doubt it would be the spark plug. How is the idle? rough? smooth? While in park how does the engine respond to brief 1/2 throttle revs? smooth? I'd put in park and hit the gas pedal a few times to see if it runs smooth if so, you will want to have the transmission checked out.

it is the abs wheel speed sensors. You have 1 sensor that goes on each tire on the car.