the engine was running rough gave tune-up 6months engine stalled wont re start

1992 Oldsmobile Cutlass S 3.1, plugs and wires changed, and does stall along but turns back on, and I just noticed bluish white smoke come out of muffler. I don't know if it's overheating because after wires/plugs were changed, none of the dash lights work, with the exception of miles/odometer.I got the car back 10xs worse than before taking it in. I have never once had a problem with this car which is I why I've kept it.