I need more details when does it spit and sputter?Idle under load certain ROMs etc?Also what kind of plugs do you put in details please?Also the wires were routed correctly you checked before you changed the wires and after you changed them?Also how is the bottom coolant temp sensor?When they go bad they will cause spiting sputtering dieing overheating no starts hard starts surging etc.Also inspect the inside of the coolant temp sensor connector if the terminals are green or blue instead of silver they are corroded and the connector needs to be replaced. Its really common or this sensors to go bad its the bottom sensor screwed into the with two wires going to it a black wire and a yellow wire.