Chevrolet: 97 chevy lumina, chevy lumina, newer cars

Question
My 97 lumina has 68000 miles on it and has been a great car. Recently it has become sluggish and it seems like the overdrive gear drops out. along with a slight vibration that is more noticible at stoplights. I've been looking at cars to buy but, would like to get more milage from this one do you think the problem is all trans related or do I also need to get my engine repaired. thanks Mark  

Answer
Mark;
HI- when was the last time that it was serviced,or the tranny fluid flushed and a new tranny filter and the fuel system also, with the newer cars they must be kept up or with all of the elect. sensors the computer will go crazy and cause trouble I would get it put on a meter to see what codes come up.