Ford Repair: mondeo judders, senser, ford mondeo

Question
i have got a mondeo n reg. it has started to judder when i start the car up from hot or cold it judders for a while and then it will eventually go and then drives fine until the next time i start it up. my garage dont really have a clue, they have just changed the lamber senser???? but they reckon it might be the catalytic converter. but my brother who owns ford mondeo says try changing the rubber t piece but surly the garage would have checked this??? please help

Answer
I can't help you with what you have stated. It will help to know engine, trans, what year, etc. I know the Mondeo is a foreign model to the US, but not which vehicle it compares to here. Also I dont undertsand the term judder.
Some more details will help.