When my mom went into assisted living I sold her 1997 Lincoln Town car, It ran as you described. It had been sitting over the summer. First thing I did was drain the bad gas. The new gas with ethanol will go bad sooner than pure gasoline. Then I filled with high test with a couple of bottles of gas conditioner. Then I changed the plugs. Then all was well. Sounds like you may have a combination fuel and ignition problems. Hope this helps a little.