A tune-up is not your problem. A coil....maybe but first: your conditions are exactly what happened to me when my fuel pump died. When you turn the ignition to Start, does the starter motor run as it should? When you turn the ignition to On can you hear a hum from the gas tank? You need the window open or someone to listen for it. If you hear the fuel pump hum, then the next thing to do would be to check for spark.
94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new
88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new