1998 Jeep Wrangler (TJ) SE 4 Cyl 2.50L
O2 sensor and spark plugs gets full carbon deposit fast
Many things will do it. Are the plugs wet or oily? It not firing hot will do it, poor plug wires, bad cap and rotor. Weak coil, low voltage to the coil. Over loading with fuel, poor compression, leaking seals, leaking injectors.