Welcome to the Team Paul!
Here at Team Impala we are focused upon the older 1958-1976 model B-bodies. All are welcome however and owning a car is not a prerequisite to join as I personally own a 1985 Impala and a 1989 Caprice. We have a few ASE certified mechanics who may be able to answer your question though it is hard to diagnose anything remotely with limited information in terms of observations.
I could hazard a guess to say that you could have issues with your transmission; or the EGR valve, or MAF sensor. If it still exists the TCS sensor could be faulty as well as there are about thirty sensors and five computers monitoring your cars functions to control what is going on electrically. If your electrical system is faulty the changing voltage that could be playing havoc with the sensors. There are a host of things it could be.
I suggest you take the car to a certified competent mechanic and have him plug it into his diagnostic computer and see what the two computers have to say to each other. The cars on this board are fixed with a screw driver which really doesn't apply to your situation.