1990 Buick Regal Surging

I have a 1990 Buick Regal Custom Gran Sport with the 3.8 liter engine. My car is doing some surging when it is running and driving. When I accelerate the car will start hesitating like it is losing power or something is not getting to the engine. I had new spark plugs put in, all 3 coil packs replaced, the ignition module replaced, my vacuum hose cleaned, my fuel filter cleaned, and a crank sensor put in. It still is doing the same thing. I also feel vibration when it idles and I feel some putting from the muffler as well. I had 4 techs look at the car and neither one of them can figure out what is wrong with my car. Code 42 came up on the computer when my service light came on which was something electrical. Someone please help me with suggestions as to what could be the problem. This is a good car and I drive it back and forth from college and it still goes but the surging and hesitating is irritating and I put a lot of money in this car and all I want to do is find out what is wrong with it.