Just go done rebuilding my motor and now the motor will not stay on in neutral unless I keep my foot on the gas pedal. Once i let go the gas pedal it will idle down and shut off the motor. Wierd thing is if I u nplug any vacuum line the motor will stay on during neutral around 700 rpm. Any one know what might cause this?

 

Do you have fresh plugs with fresh plug wires and a nice ignition coil?

 

Yes, everything is brand new with the build

 

Make sure you have good grounds. I just swapped ny motor earlier this week too, had the same problem, but as i was going to test my dizzy, i found out thaf the ECU ground on the engine harness wasnt properly grounded.

That ground is located on the back of te block on the thermostat housing nesr thh water pipe.

 

all grounds are connected