Originally, the vehicle would run 2-3 minutes, then die. MIL: off. After replacing the fuel filter, the engine would run longer, but the scanner showed engine timing to be as high as 35 degrees advanced, with extreme pre-ignition issues. TPS is smooth from 0% to 100%. O2 sensors indicating proper voltages, with no cat. conv. issues. Fuel pump runs as it should, with good pressure. The vehicle has 157,00 miles on and it and it is not known how long it has been since the plugs were last replaced. Our next step is to replace them. Any suggestions would be appreciated.