We have taken it to the shop and they can only find spark plugs that are bad. All the plugs were replaced and a week after its been out of the shop it is jerking again. After awhile the check engine light will come on. It jerks to the point where it feels like it is going to stall and when you give it gas it sputters. Please help cause the mercury/lincoln dealer we take it too can not fix it.

Its because they do not care and have no insentive to fix anything, they get a pay check no matter what, take it to a local garage. It sounds like you have a transmition problem, but l couldnt tell unless l had a look, remember the local guy needs your money to stay open (take it to a trusted machanic, or one a friend recomends, some have a tendency to jerk you around)

ck the spark plug wires. get a spray bottle with soapy water in it. while running the egine spray the spark plug wires. it the engine starts to run rough while you are spraying them then the spark plug wires are bleeding through and need to be replaced.