my car was slightly shaking or viberating when stopped at the stop light on 1998 Infiniti Q45

then the service engine soon light came on. The mechanic is suggesting to replace injector and two coils (one and three)
What should I do

Asked by for the 1998 Infiniti Q45
if you trust your mechanic, follow his/her advice. preventative maintainance for future reference is key to happy vehicle.
The cost to do that he is asking for $1200. I am not sure if that price is ok. I had replaced all coils in 2009 and after that I drove about 10,000 miles. Is it worth spending this much money on this car