04 ford ranger, idle at 3000 RPM?

Question

After starting the RPM will gradually lower to about 1000 RPM, then shoot up to 3000 RPM and stay there. what is wrong?

this just started after i replaced the thermostat and thermostat housing due to a crack in the housing and overheating.

Answer 1

Hi there

This could be the result of a vacuum leak, or a problem with the coolant temp sensor. Sometimes when they get hot the sensor itself can go bad.